Which of the following answers matches “the quotient of 9 and the sum of the quantities 5 and product of 8 and x.”
a. 8+5 9
b. 9(5 + 8)
c. 8 9 + 5
d. 8+5 9
in advance

This answer isn't listed, but likely choice B seems to be the closest. Check to make sure there aren't any typos.

How did I get that answer? Well the phrase "product of 8 and x" means "8 times x" or simply 8*x. The asterisk means "multiply". Often we can drop the asterisk to say 8x and mean the same thing. Multiplication is implied here.

"sum of 5 and product of 8 and x" turns into "sum of 5 and 8x" which becomes 5+8x

Finally, the term "quotient" is the result of a division. We will divide 9 over all of (5+8x). I use parenthesis so we know that everything but the 9 is in the denominator

That's how we end up with the answer 9/(5+8x)

Or you can say "9 over (5+8x)" or something along those lines. The slash bar is often used for fractions and division.

add 8+12 to get a simplified answer of 12r-20