Can someone pls help i will give brainliest

Anyone know? is appreciated! will mark brainliest if correct!

Evaluate cos2θ for cosθ = square root of 3/2

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.