Is (5,15) a solution of the equation y=3x?

What are the sotions to the quadratic equation 9x^2=4

How many solutions does the nonlinear system of equations graphed bellow have?

Kristen is wrapping presents for the holidays. she has a box that measures 4 ft. x 2 ft. x 2 ft. how many square feet of wrapping paper does she need to cover the box without overlapping?