If the sum of a number and eight is tripled the result is nine less than twice the number. Find the number

3 (x + 8) = 2x - 9

Distributive property.

3x + 24 = 2x - 9

Subtract 24 from both sides.

3x = 2x - 33

Subtract 2x from both sides.

x = - 33 (this is your answer)

We can plug this value into the original equation to verify if it's correct.

3 (x + 8) = 2x - 9

3 (-33 + 8) = 2 * - 33 - 9

-75 = - 75 √ this is correct