Melony makes $21 of profit every time she sells 3 shirts and four times as much profit when she sells two pairs of sandals. How much profit will she make if she sells 7 shirts and 3 pairs of sandals? Let's answer step by step:
Melony makes $21 * 4 = $84 of profit for two pairs of sandals. Melony makes $84 / 2 pairs = $42 of profit per pair of shoes. Melony makes $21 / 3 shirts = $7 of profit per shirt. For seven shirts, Melony will make 7 shirts * $7 = $49 of profit. For three pairs of sandals, Melony will make 3 pairs * $42 / pair = $126 of profit. Melony will make a total of $49 + $126 = $175 of profit. The answer: 175.