This Question is based on the Law of Exponents

a^m * a^n = a^(m+n) (and vice-versa)

Now, your Left hand side has 5^m and 4^18
4 can be written as 2^2 so 4^18 = (2^2)^18 = 2^36
(According to Law of Exponents (a^m)^n = a^(m*n) )

Your Right hand side has 10 which is the same as 5 * 2
So (5*2) ^ 35 = (5^35) * (2^35) (see top)

Therefore m = 35

p.s. I have ignored the fractional part since the numerator is 1 and therefore doesnt affect the answer.