Question

Write an equation. Let x be the unknown number.

Eight less than twice a number is 10.

Answer 1

Since our unknown number is x and we are writing an equation, the eight less than a number will be on one side where the number is x, and on the other side is 10. So,
10=2x-8

Answer 2

2x - 8 = 10. 
Twice a number is 2x.
8 less than that number is minus 8.
Is ten is =10.