mix problems

[chucks]

I am doing this problem on acid solution. I dont know how they get this answer.
0.34x+0.18y=0.28(30)
34x+18y=28(30)
how do they get 34x+22Y=840 HOw do they get the 22y in the middle how do they end with 16x+0y=-540

 

[Mrspi]

I am doing this problem on acid solution. I dont know how they get this answer.
0.34x+0.18y=0.28(30)
34x+18y=28(30)
how do they get 34x+22Y=840 HOw do they get the 22y in the middle how do they end with 16x+0y=-540

The fact that you have given us ONE equation with TWO variables makes me think that we aren't seeing the whole problem.

Please type the original problem exactly as it appears in your text...maybe we can help then.

 

[mmm4444bot]

Given:

0.34x + 0.18y = 0.28(30)

Multiply both sides by 100

34x + 18y = 28(30)

Simplify the righthand side

34x + 18y = 840

how do they get 34x + 22y = 840

They made a mistake.

If you follow Mrs. Pi's suggestion, we can help you to work the exercise properly.

 

[bcindyfree]

I am in need of help with a mixed problem. The problem is 5lb/ft x 3ft. I do not know what the first step is. I appreciate your help thank you.

 

[mmm4444bot]

The problem is 5lb/ft x 3ft No, it is not.

Five pounds per foot times three feet is an "expression", not a problem. A problem always comes with instructions.

I'll guess that you were told to simplify the given expression.

I do not know what the first step is.

The first step is understanding the meaning of that expression.

Sometimes, it helps to have a real-world image, in your head.

Let's say that we want to buy a 3-foot length of big steel pipe. It's thin pipe, but who knows? Will we be able to lift it into our car?

The weight rating of this particular kind of pipe is: 5lb/ft.

What this ratio means is that every one-foot section of pipe weighs 5 lbs.

It's used as a rate, so that people can multiply it by the number of feet they plan to buy, in order to determine how much their purchase will weigh.

If I were to buy a 20-foot section of pipe, I would calculate its weight by using the rate.

\(\displaystyle \frac{5 lb}{ft} \times 20 ft = 100 lbs\)

Notice how the feet units cancel, leaving only the pounds unit.

Viewing the arithmetic and units analysis separately, we have:

\(\displaystyle \frac{5}{1} \times \frac{20}{1} = \frac{100}{1}\)

\(\displaystyle \frac{lb}{ft} \times \frac{ft}{1} = \frac{lb}{1}\)

The arithmetic is straightforward, and the \(\displaystyle ft\) units on top and bottom cancel, leaving \(\displaystyle lb\) on top.

The net result of the multiplication of the rate times the number of feet is 100 lbs.

Are you now able to simplify your given expression ?

PS: In the future, please start your own thread, by clicking the [NEWTOPIC] button located on the boards' index pages.

 

[bcindyfree]

Hello. Thank you for your help. Yes, I am now able to simpifly the expression. My answer is 15lbs. Thanks again!