need some help with a test at work, been out of school for 20yrs

[SapperLex]

20cc's into 100cc's, then take 5cc's of that and add to another 100cc's. how much higher is the concentration of the original from the end?
and could you simplify the answer i need to learn how and why.

i have a fraction question but dont know who to set that up on here going to try my best...
3.6 2.34
_ = _
4 X what is X. i get as far as 4x2.34=9.36 but dont know where to go from there, not even 100% sure thats right.

any help is appreciated, math has always been the bane of my existance.

 

[SapperLex]

ok im not getting all the symbols in the first questions, so ill skip that for now and work on it after i post this. ok lets see if i get the first one
20+100=120, so then you take 5 120ths or (im guessing) 5/120, and 5+100=105 i get, then it all goes south.
i think the symbols are throwing me, everytime i see / i think divide.
So, [(5/120)s] / 105 = 5s / (120 * 105) = s / (120 * 21) = s / 2520
And 2520 / 20 = 126.
i cant tell what are fractions and what are division. i can go backwards and see that 126 is 2520/20, and 2520 is 120*21, but thats where i get stuck, i cant get past there. i dont know why 120 times 105 is there.


the 2nd question(if i get the symbols right) would be

3.6/4=2.34/x i hope thats right
so i did the cross multiply and got 4*2.34=9.36

so then i should divide 3.6 by 9.36 to get 2.6 which is X?

btw thanks for putting up with me.

 

[SapperLex]

thank you denis and jeff, im glad that youve explained the 2nd question so that i get it but im still stuck on the 1st one.

ok jeff i get(i hope) what you are saying that / doesnt matter because a fraction is just a division that hasnt been finished.
im having a very hard time visualizing the work through on the 1st.

[(5/120)s] / 105 = 5s / (120 * 105) = s / (120 * 21) = s / 2520
And 2520 / 20 = 126.

god let me see if i can show you what i see...im going to skip the first part atm since 12hr shifts all week have left me dumber than usual.

........5............. s
------------ = ---------- = and since s is 20 its 126......i could have the wrong numbers on top im going mostly on guesswork. ignore the .'s it keeps compressing it
(120*105)...... 2520


i know that the begining is 20+100=120 and 5+100=105, so im going to skip that since math that simple i have. the figure i have above might not be the best way to show it but i just need the result, if what i have gets me to that goal id be happy.

take the 2 totals multiply them then divide by the number you want the percent of then by the original. it might be bass ackwards but if its right ill use it.......i just hope its right.
and the 126 is that a % or just the total and id have to convert?

 

[SapperLex]

ok thanks for putting into fractions that i can see, makes it alot easier to visualize.

where im hung up is right in the middle.

i see 5s over 120 times 105 so i get 5s over 12600. then i divided 12600 by 5 and get 2520. i seem to be getting the same answer and i dont get the
5s over 120 times 21. and i have no idea why.


i also have questions about the -1 for the % at the end but let me take 1 at a time.

 

[SapperLex]

ok cool, as long as im getting the CORRECT answer and its not by luck then i feel better and ill practice on it more. i might not be above water yet but at least my nose has broken the surface

as far as the % formula, at work we use original-current/original, then convert.

say its 20-10=10/20=0.5 or 50%

what you showed me a few posts ago had a -1 in the formula and i was confused all over again
maybe its more info then i need for now, or im missing something.

 

[SapperLex]

ok so like the CC one its same answer different direction getting there.

thanks for all the help denis and jeff, hopefully i wont have to bug you guys again.