Answer:

Explanation:
1. General concept about exponents.
When working with positive non fractional exponents, we state that a number A elevated to the n power is that number A in a multiplication of itself n times. For example, when we write
we're stating that the seven is being multiplied 3 times:
.
2. Use the rule to rewrite the expression.
As you may see, the expression "15*15*15*15" is just the number 15 being multiplied by itself four times. Hence, we could say that the number 15 to the power of 4. Thus, we can rewrite it as:
