Algebra Review!! I keep getting answers that don't make sense. Help?

Question

The problem is:
4/5a = -20
Do I divide or multiply -20 by the 5 in 4/5? This gets -100.
Or do I divide 4/5 = .8 and multiply that by -20? This gets -16.
Neither one make any sense in the problem.
:0:OXO

Answer 1

Think of the numerator and denominator.

On the left, the numerator is 4a and the denominator is 5

On the right, the numerator is -20, and the denominator is 1

If you divide the right and left by -20, you get a/-25=1. Then multiply both sides by -25 and you get a=-25

If you start by multiplying both sides by 5, you get 4a=-100. Then divide both sides by 4 and you get a=-25 Same answer

If you start by dividing both sides by 4, you get a/5 = -5. You then multiply both sides by 5, and you get a=-25.

The last approach is to divide both sides by a, which gives you 4/5=-20/a. Then divide both sides by -20, and you get 1/-25=1/a. Multiply both sides by -25, you get 1=-25/a. Then multiply both sides by a to get -25=a.

Answer 2

You're trying to find a so take -20 and divide it by 4/5 (which is the same as .8)

Answer 3

4/5a=-20

you mutiply the reciprocal of 4/5 on both sides(the reciprocal is 5/4), so,

5/4 x 4/5 = -20 x 5/4

the answer is a= -25
to check the input -25 in for a you should get -20, lets check

4/5 x -25 = -20

Answer 4

a= -25

4/5a= -20
*5 4/5a= -20*5
4a= -100
a= -25

Answer 5

4/5a=-20
a=-20*5/4
a=-25