An exponent is a number written above and to the right side of a value or number in math. The value or number is called the base, and the expression is read out as;
"Base raised to the power of exponent."
An example is given below;

In this example, 10 is the base and 3 is the EXPONENT.
The expression is now read out as,
"10 raised to the power of 3"
Note that even unknown values (such x as we commonly use in math) can also be an exponent or base. For example, we can have;

So basically, an exponent indicates the number of times a number is used to multiply itself.
D) 2.1+2x=7.5
All the sides added together will equal the perimeter
Answer:
43.9823
Step-by-step explanation:

Is there any answer choices so I can choose?
Answer:
Ava is 10 years old
Step-by-step explanation:
Sara is 8
Sara=$8 per week for 12 weeks
$8×12 weeks=$96
Ava has $24 more than Sara
x*12=96$+$24
12x=120
x=120/12
x=10
Ava's age is 10