Question 13
Find the digits represented by $a$ and $b$ in $\overline{a7889b}$ so that it is divisible by 15.
Answer entry: enter any valid pair a;b. The solution lists all valid pairs.
**Editorial input note:** Use no spaces before or after semicolons.
Answer entry: enter any valid pair a;b. The solution lists all valid pairs.
**Editorial input note:** Use no spaces before or after semicolons.