Which expression can be substituted for x in the top equation of the following system to solve the system by substitution? 2x−7y=15 x+4y=6

Which shows the correct solution of the equation 1/2a+2/3b=50, when b=30?

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)) =

Amovie streaming service charges it’s customers $15 a month. martina has $98 saved up. will she have any money left over if she pays for the maximum amount of months she can afford? explain.