Answer: last option.
Step-by-step explanation:
According to the Product of powers property, you have:
As you can see, when you can add the exponents when you have powers with equal base.
Then, 
and 
do not have the same base, therefore, the exponents can't be added.
Therefore, Eli is incorrect, because he added the exponents even though the bases are not the same.
Answer: 18.86 feet
Step-by-step explanation:
The formula for determining the circumference of a circle is expressed as
Circumference = πD
Where D represents the diameter of the circle.
The circumference of the inner circle is 44 ft. It means that
22/7 × D = 44
22D = 7 × 44 = 308
D = 308/22
D = 14 ft
The distance between the inner circle and the outer circle is 3 ft. This means that the diameter of the outer circle would be
14 + 3 + 3 = 20 ft
Circumference of the outer circle is
22/7 × 20 = 62.86 ft
The number of feet by which the circumference of outer circle is greater than the circumference of the inner circle is
62.86 - 44 = 18.86 feet
F(x)=2x+3-(x+10)
0=2x+3-x-10
0=x-7
-x=-7
x=7
21²=21×21
21×21=441
2,870+441=3,221
