Super desperate

C

charlyjohnston

New member
Joined
Feb 14, 2006
Messages
6
Hey - I am a total moron and need help with my algebra homework. I can't figure out these problems... I have two.

Solve by elimination methd:

1.
5r-9s=1
9r+5s=23

2.
One day a store sold 26 tshirts. Total amount - $290.75. white sold for $10.95, yellow sold for $11.50. How many of each color were sold?

I don't know how to set this problem up... I have three like this that I don't know what to do with. HELP!

If any one can help me, I would be SO grateful!
 
1) Multiply the first by 9 and the second by 5

2)w is how many white were sold
y is how many yellow were sold
w+y=26
10.95w + 11.50y=290.75
 
OK- - so this is what I have done with #1... Is this wrong?

5r-9s=1
9r+5S=23

5r(5)-9s(5)=1(5)
9r(9)+5s(9)=23(9)

25r-45s=5
81r+45s=207

25r+81r = 207

106r=207

r= 207/106
 
charlyjohnston said:
25r-45s=5
81r+45s=207

25r+81r = 207
Click to expand...
Oh, you're so close!

Try adding the right-hand sides again. Then divide through by the 106.


Eliz.
 
OK, i got the 106r=212

:) I know - how silly.

R=2.

I have to enter the ordered pairs. I know one will be 2, but then how do I know what the other one will be?
 
I still have NO clue what to do with the word problem. You have

w is how many white were sold
y is how many yellow were sold
w+y=26
10.95w + 11.50y=290.75


I am really at a loss on what to do. I am so frustrated I can hardly stand it! Thank you for your help!
 
charlyjohnston said:
I still have NO clue what to do with the word problem. You have

w is how many white were sold
y is how many yellow were sold
w+y=26
10.95w + 11.50y=290.75


I am really at a loss on what to do. I am so frustrated I can hardly stand it! Thank you for your help!
Click to expand...

I hope you understand where these equations come from. The first comes from the fact that 26 t-shirts were sold. The second comes from the fact that $290.75 was the amount obtained from the sale of w white t-shirts at $10.95 each, and y yellow t-shirts at $11.50 each.

This system can be readily solved by substitution. Take the first equation,
w + y = 26
Solve for either w or y; I'll solve it for w:
w = 26 - y

Now, substitute (26 - y) for w in the second equation:
10.95w + 11.50y = 290.75
10.95(26 - y) + 11.50y = 290.75

This equation has just one variable; you should be able to solve it for y. Once you know the value of y, remember that w = 26 - y and find the value of w.

I hope this helps you.
 
You must log in or register to reply here.
Top