Please help it's due in a few minutes

Another type of subtraction equation is 16-b=7. explain how you would sole this equation then solve it.

Find the volume of the solid whose base is the region bounded by f(x), g(x) and the x-axis on the interval [0, 1], and whose cross-sections perpendicular to the y-axis are squares. your work must show the integral, but you may use your calculator to evaluate it. give 3 decimal places for your answe

What is the gcf of 20c^3-5c^4+30c^6