Question

When the number of marbles Jill has is subtracted from 20, the result is the same as adding 16 to the number of marbles.

How many marbles does Jill have?

Is it 20 - x = x + 16 and how do I find x

Answer 1

First, yes, it is 20 - x = x + 16. Now here's the calculation to get x:

20 - x = x + 16 | + x
20 = x + 16 + x =
20 = 2*x + 16 | - 16
20 - 16 = 2*x =
4 = 2*x | / 2
4 / 2 = x =
2 = x

Jill has two marbles.