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
$( {x}^{2} - 8) \div 7 + 12 = 20$
$( {x}^{2} - 8) \div 7 = 8$
$( {x}^{2} - 8) = 56$
${x}^{2} = 64$
$x = \sqrt{64} \: \: \: \: \: x = - \sqrt{64}$
$x = 8 \: \: \: \: \: x = - 8$