Twice the sum of a number and nine is 24. Find the number.

3

Step-by-step explanation:

2 (n + 9) = 24 this is the equation

to solve for n (number):

2(n+9)=24 // Distribute the 2 into parentheses

2n + 18 = 24 // Subtract 18 on both sides of equal sign

      - 18   -18

      2n = 6 // Divide by 2 on both sides of equal sign

        2     2

      n = 3

Hope this helps :)