Hello i need help please

Simplify the expression. -2/5(10+15m-20n)

If t17 = 3 (t5) in an arithmetic progression, find t1 in terms of d.

Find the equation of the ellipse with the following properties. the ellipse with foci at (0, 6) and (0, -6); y-intercepts (0, 8) and (0, -8).edit: the answer is x^2 over 28 + y^2 over 64 = 1