What does a equal if 9a is equal to 36?

Answer 1

9a = 36

9a/9 = 36/9

a = 4

Explanation:

To answer this equation we must get "a" all by itself on one side. "a" is an unknown variable that as far as we know right now, could be anything. "9a" really means "9 times a" (or that we have 9 "a's"). To get "a" by itself we have to divide "9a" by 9. This will give us "1a" which is the same as just saying "a". In algebra the equation must stay constant. Whatever you do to one side you must also do to the other. This means we must also divide 39 by 9. Our final equation will be "a = 4".

There are two quick methods we can use to check our answer:

1)

With algebraic expressions we can check our answers by working backwards. If we take "a = 4" and now multiply both sides by nine what do we get? Well "a" times 9 would be "9a" (as we mentioned before, "9a" really just means 9 times "a"), and 4 times 9 is 36. So again we have 9a = 36. "a" must equal 4.

2)

We can also check our answer by substituting the final answer for "a" in the place of "a" in our original question and then solve it to see if it is true. So "9a = 36" becomes "9 times 4 = 36" (recall again that "9a" really just means "9 times a"). 9 times 4 is 36 so our final answer becomes "36 = 36", therefore we have the correct answer. "a" must equal 4.