Can I please have help answering questions 7-9? Thank you!! This is Math Modeling

A small manufacturing plant produces three kinds of bicycles - three-speed, five-speed, and ten-speed - in two factories. Factory A produces 16 three-speeds, 12 five-speeds and 30 ten=speeds in one day, while Factory B produces 15 three-speeds, 18 five- speeds and 20 ten-speeds in one day. An order is received for 30 three-speeds, 40 five-speeds, and 50 ten-speeds. It costs $1200 a day to operate factory A and $3000 a day to operate factory B. The manufacturer chooses the number of days to operate each factory in order to minimize cost. 7. In the situation above, the variables are (9\\- r-) (0 A) x = the total cost to operate factory A, y = the total cost to operate Factory B B) x = the number of three- speed produced, y = the number of five-speeds produced, z = the number of ten-speeds produced e paiwollot erlt ovloa C) x = the number of days factory A is operated, y= the number of days factory B is operated. D) x = the number of days spent producing three-speeds, y = the number of days spent producing five-speeds, z = the number of days spent producing ten- speeds. (8-4) (8 (0.v) (3 8. In the situation above, the objective function is (F-.0) ta A) 3000x + 1200y B) 1200x + 3000y rum -T C) 58x + 53y imum # 98 D) 30x + 40y + 50z 9. In the situation above, which of the following constraints must be satisfied? A) 30x+20y