If 8a + 2b + 7c = 4, what is -7c - 2b - 8a

Factor -8x3-2x2-12x-3 by grouping what is the resulting expression?

Can someone explain to me how to do

Thanh and her crew are building a stage in the shape of a trapezoid for an upcoming festival. the lengths of the parallel sides of the trapezoid are 14 ft and 24 ft. the height of the trapezoid is 12 ft.what is the area of the stage? enter your answer in the box. ft²