SOMEONE HELP ME PLEASE I DONT KNOW HOW TO DO THIS!!!

if you're a tad confused, o represents one of the options and you're supposed to fill it in. x represents number for bags

A coffee shop sells bags of coffee for a regular price of $8 per bag. Chang bought some bags and used a coupon for $10 off his entire purchase. After applying the coupon, he paid $30.

How many bags of coffee did he buy?

(a) Write an equation to help answer the question above.
Choose the correct form below and fill in the blanks using only 8, 10, and 30.
(The variable x is used to represent the number of bags.)
ox+o=o OR o×-o=o

(b) Write an expression to help answer the question above.
Choose the correct form below and fill in the blanks using only 8, 10, and 30.
o+o/o OR o-o/o

(c) How many bags of coffee did Chang buy? answer: _x_ bags ​