Question

Andrew is trying to create a number puzzle for his younger sister to solve. He challenges his sister to find the mystery number. “When 4 is subtracted from half of a number the result is 5.” The equation to represent the mystery number is 12m − 4 =5. Andrew’s sister tries to guess the mystery number. Her guess is 30. Is she correct? If she isn't correct, what value for m would be correct?

Answer 1

$\begin{gathered} \frac{1}{2}m-4=5 \\ \frac{1}{2}m=9 \\ m=18 \end{gathered}$

she is not correct, the right answer is 18