Question

add 15 with a number then subtract 10 and you will get 25. What is the number?​

Answer 1

Let the unknown number be x

$15 + x - 10 = 25 \\ x + 5 = 25 \\ x = 25 - 5 \\ x = 20$

The number is 20.

Verification :

$15 + 20 - 10 = 25 \\ 35 - 10 = 25 \\ 25 = 25$

Hence, verified ✔️