Question

A student chose a number, multiplied it by 2, then subtracted 138 from the result and got 102. What was the number he chose?

Answer 1

Answer: 120

2x - 138 = 102
+138 +138
(x=the missing number)

2x =240

240\2 = 120

x=120

Answer 2

51

Explanation:

let's set the starting number as x

1. x times 2 = 2x

2. 2x- 138

3. result = 102

So, 2x-138 = 102

Now lets work backwards to solve for x.

1. 2x = 102

x = 51

So the starting number was 51.