The region to be painted is shown by the brighter coloured shapes, that is the triangles. (Note that they do not paint the base of the climbing wall, hence the square base in red is excluded).
The area of all four triangles is given as;
Therefore, for 4 of such triangular shaped sides, they would need
48 times 4 square feet of paint
That means 48 x 4 = 192 ft^2
That is, they would need enough paint to cover 192 square feet of wall space