A business owner is comparing the cost of buying natural gas from two different companies. • Company A charges a $6 fee plus $1.25 per therm (unit of heat).
• Company B charges a $9 fee plus $0.75 per therm (unit of heat).
For what number of therms will the cost be the same at both companies?
13.5 therms
9 therms
6 therms
12.75 therms

Will mark brainliest question in the pic.

Someone answer this asap rn for ! a discount store’s prices are 25% lower than department store prices. the function c(x) = 0.75x can be used to determine the cost c, in dollars, of an item, where x is the department store price, in dollars. if the item has not sold in one month, the discount store takes an additional 20% off the discounted price and an additional $5 off the total purchase. the function d(y) = 0.80y - 5 can be used to find d, the cost, in dollars, of an item that has not been sold for a month, where y is the discount store price, in dollars. create a function d(c(x)) that represents the final price of an item when a costumer buys an item that has been in the discount store for a month. d(c(x)) =

Math i have no idea how to do a and b