Hiya I need some help with 2 questions, please help;)

A person living in an apartment puts down a $300 deposit when they move in and then pays $700 of rent each month for a year. If the apartment is in good condition when they move out, then they get the deposit back. Write an expression to represent the housing cost for this situation if the renter gets the deposit back at the end of m months.

a. 300+700m

b. 700+300m−700

c. 700m−300

d. 300+700m−300

How many variables are in the expression 4b^2+3?

a. 4

b. 3

c. 1

d. 2

3 answers

d. 300+700m−300 and d. 2
thx so much!
wait, d. 2 was incorrect its actually 1