You will just get 18 feet 3inches or 18.3 feet
I dont know how to this but you probably make 4 3/8 and 2 1/2 into a decimal add all them together...

the first step is to deal with the negative exponents, which causes numbers to go to the other side of the fraction
8x^{-9}+(-3x^{-3}y^{-2})(\frac{5}{x^6y^{-2}})
goes to

now we can simplify the multiplied terms

Now that we have common bases, we can add the 2 fractions together to get

Answer is D. 3(x - 7) = 3x - 21
because
3(x - 7) = 3x - 21
Distributive property
3x - 21 = 3x - 21
0 = 0
Infinitely many real solutions