I'm confused on the equations. am i supposed to do two of them? 27.50=4p+2d and 18.25=2p+3d?

An objects motion is described by the equation d= 4sin (pi t) what will the height of the object be at 1.75 seconds?

Someone answer asap 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)) =

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.