I cant figure out what the answer is

3x + 4y = 5 x- 3y = -7 solve by substitution

Suppose that the price p, in dollars, and the number of sales, x, of a certain item follow the equation 4 p plus 4 x plus 2 pxequals56. suppose also that p and x are both functions of time, measured in days. find the rate at which x is changing when xequals2, pequals6, and startfraction dp over dt endfraction equals1.5.

Suppose 38 lbs of coffee beans are required to produce 2 lbs of farmer's coffee. how many lbs of coffee beans are required to produce 309 lbs of farmer's coffee?