Question

Dennis thought of a number. He adds 0.5 to that number and then multiplies the new result by 4. He then subtracts 2 and divides the number by 2. His final answer is 48. What number did Dennis start with?

Answer 1

Let the x be the number 
So,
             (4(x+0.5)-2)/2=48
So,
              x=24 is the number.

Answer 2

Let the number Dennis thought be x.

He adds 0.5 to that number and then multiplies the new result by 4.

The new number now is 4(x+0.5) He then subtracts 2 and divides the number by 2.The new number formed is $\frac{4(x+0.5)-2}{2}$

Given His final answer is 48.

We can form an equation in x.

$\frac{4(x+0.5)-2}{2} =48$

To solve for x we multiply both sides by 2 to get

4(x+0.5)=96

4x+2=96

Subtracting 2 both sides

4x=94

Dividing both sides by 4:

x=24.

The number Dennis thought is 24.