Need Help With Exam To Get Job........

[dnorr]

I have to take an algebra based exam for employment. Use of a calculator is not permitted. I was sent to a web page with similar problems that will be on the exam. They show you how to get the answer to the problem but they don’t show you how to do the math to derive the answer. For example, in the following problem (see attachment), how do they derive at x = 31,250 from –0.08x = –2,500? What is the calculation used to derive at this? The actual web page is http://www.purplemath.com/modules/investmt.htm. Thanks.

 

[Deleted member 4993]

I have to take an algebra based exam for employment. Use of a calculator is not permitted. I was sent to a web page with similar problems that will be on the exam. They show you how to get the answer to the problem but they don’t show you how to do the math to derive the answer. For example, in the following problem (see attachment), how do they derive at x = 31,250 from –0.08x = –2,500? What is the calculation used to derive at this? The actual web page is http://www.purplemath.com/modules/investmt.htm. Thanks.

If A * x = B (and A & B are not equal to zero)

then

x = B/A

 

[dnorr]

Still not very clear. It's been years since I've done this. Can you use this example to illustrate –0.08x = –2,500? Thanks.

 

[masters]

Still not very clear. It's been years since I've done this. Can you use this example to illustrate –0.08x = –2,500? Thanks.

Hi dnorr,

\(\displaystyle -0.08x=-2500\)

The idea here is to 'isolate' the variable \(\displaystyle x\).

In the above equation \(\displaystyle x\) has been multiplied by \(\displaystyle -0.08\) on the left side.

To undo multiplication we must divide. We shall divide both sides of the equation by \(\displaystyle -0.08\)

That should free up our \(\displaystyle x\) rather nicely.

\(\displaystyle \frac{-0.08x}{-0.08}=\frac{-2500}{-0.08}\)

The equation now simplifies to

\(\displaystyle x=\frac{-2500}{-0.08}\)

Now, just do the division on the right to arrive at

\(\displaystyle x=31250\)

Can you do the long division without a calculator?

 

[Denis]

Can you use this example to illustrate –0.08x = –2,500? Thanks.

As easy/simple as: 3 apples cost 75 cents; one apple costs?
a = apple
3a = 75
a = 75/3 = 25 cents
Similarly:
-.08x = -2500
x = -2500 / -.08 = 31250

REMEMBER that if you multiply or divide 2 negative amounts: result is positive.

 

[dnorr]

Hi masters,

Thanks...that helped a lot. And, yes I may have difficulty doing the long division without a calculator. If you can help with that I would really appreciate it. Thanks also Denis.