Dot sold 158 T-shirts and 107 shorts.
From the given information, we can write the following 2 equations.
x + y = 265
2x + 3y = 637
Multiply the top equation by 3 and use the elimination method to solve.
3x + 3y = 795
2x + 3y = 637
x = 158
If she sold 158 T-shirts, she must have sold 107 shorts.
265 - 158 = 107