Let L = the length of the tennis court
Let W = its width
We have two unknowns (L and W), so we need two equations to solve for the unknowns.
Equation 1: The perimeter of a standard tennis court when used for doubles play is 228 ft
The perimeter is the distance around the outside of the tennis court. Starting from a corner, you walk one length, then turn and walk along the width, the turn and walk another length, then turn and walk another width to get back to where you started. So you walked two lengths (2L) and two widths (2W), and that distance is 228 feet.
2L + 2W = 228
Equation 2: The width (W) is 46ft less (-46) than the length (L):
W = L - 46