IMSO 2018 — Math Division — Short Answer Question 22

It is known that $\overline{AMMM}$ and $\overline{MMMB}$ are two 4-digit numbers, where $A$, $B$, and $M$ are different digits. If $\frac{\overline{AMMM}}{\overline{MMMB}}=\frac25$, find the value of $A+B+M$.