Can someone please help or explain on how I can do this

Me find the value of x each figure.

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.

Which equation represents a direct linear variationa. y=x2b. y=2/5xc. y=1/xd. y=x+3