Question

Amina thinks of a number and subtracts 5/2 from it. She multiplies the result by 8. The final result is 3 times her original number. Find the number ?

Answer 1

Define x:

Let the number Amina think be x

Amina subtracts 5/2 from it

=> x - 5/2

She multiply the result by 8

=> 8(x - 5/2)

The final result is 3 times her original

=> 8(x - 5/2) = 3x

Find the number:

8(x - 5/2) = 3x

8x - 20 = 3x

5x = 20

x = 4

Answer The number is 4

Answer 2

Here is your answer

$\rule{135}{1}$

Let the number that Amina thinks be x

She subtracts $\frac{5}{2}$ from x = x - $\frac{5}{2}$

She multiplies the result by 8 = 8(x - $\frac{5}{2}$)

The final result is 3 times = 3x

According to the question,

8(x - $\frac{5}{2}$) = 3x

8x - 20 (By cancelling the values) = 3x

8x - 3x = 20

5x = 20

x = $\frac{20}{5}$

x = 4

∴ The number thought by Amina is 4