What is one third of a number that is 10 less than the number itself?

one third of a number that is 10 less than the number itself = 15

Let x = the number

1/3 of a number = 1/3 * x

10 less than the number itself = x - 10

Equation: 1/3 * x = x - 10

multiply the equation by 3

(1/3 * x = x - 10) 3

3/3 x = 3x - 30

x - 3x = -30

-2x = -30

-2x/-2 = -30/-2

x = 15