If the sum of a number and nine is doubled , the result is eight less than the number. Find the number.

Equation

Let the number = x

2 * (x + 9) = x - 8

Solve

2 (x + 9) = x - 8 Remove the brackets on the left

2x + 18 = x - 8 Subtract x from both sides

2x - x + 18 = - 8 2x and - x will combine

x + 18 = - 8 Subtract 18 from both sides

x = - 8 - 18

x = - 26

Check

LHS

2 (-26 + 9)

2 (-17)

-34

RHS

x - 8

-26 - 8

- 34 and the RHS = LHS and they check

Your number would be - 26

Sorry if this is wrong but I'm pretty sure its right