Using trig to solve triangles

Find angle A.

Find the average rate of change for f(x) = x2 − 3x − 10 from x = −5 to x = 10.

X/y + 4y/x divided by x/y - 2y/x explain as in depth as you can how you simplfied the fractions. i don't know where to start on this : /

3c2 + 2d)(–5c2 + d) select all of the partial products for the multiplication problem above.