22 small frames = 22 * $4 = $88 not enough money
21 small frames + 1 large frame = 21 * 4 + 17 = 101 not enough money
By buying 1 large frame instead of a small frame, she spent $13 more.
127 is 26 more than 101, so she bought 2 more large frames than the 1 in the second calculation above.
19 small frames + 3 large frames = 19 * 4 + 3 * 17 = 76 + 51 = 127
Answer: She bought 3 large frames and 19 small frames.