The rules of exponents tell you that you can distribute the exponent to each of the factors. When one already has an exponent, those exponents multiply.
M = 72
Your main goal in this equation is to isolate m or in other words leave m alone in one side of the equality.
All you need to do is multiply 4 in both sides for you to eliminate the denominator attached to m.
Saying this,
(M/4)(4) = (18)(4)
M = 72
The answer is 18.6. The double negative (minus a negative) equals a positive. So you add 14.3 + 4.3 = 18.6
