PLZZ HELP ASAP Which statement is true?

a. An acute triangle sometimes has a right angle.
b. A right triangle never has an obtuse angle.
C. An equilateral triangle sometimes has a right angle.
d. A quadrilateral never has an obtuse angle.​

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.