The attendance on the first night of a play was 435. The attendance on the third night was 545. If the attendance increases at a linear rate then how many people can be expected on the 6th night

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.