Question

Joseph squares a number and subtracts 8 from the answer. He then divides this result by 7. Finally he adds 12 and the result is now 20. What was Joseph's original number?

Answer 1

Let the number be X, then we find

`( {x}^(2) - 8) / 7 + 12 = 20`

`( {x}^(2) - 8) / 7 = 8`

`( {x}^(2) - 8) = 56`

`{x}^(2) = 64`

`x = √(64) \: \: \: \: \: x = - √(64)`

`x = 8 \: \: \: \: \: x = - 8`