The given expression is,

Exponents are used to express large numbers in shorter form to
make them easy to read, understand, compare and operate upon. If we write,

a is the base and m is the power. So for an expression where, a constant base with different powers are being multiplied, we have, from the property of exponents,

Using the same property of exponnets, we can write the given expression as,

Thus the answer is r^31.