Answer
[$45 *for Mrs. Robert's perm*] + [2(8) *for each of her two childrens' cuts*] + [2(3) *since each of her kids had blow-drying and styling*]
Step-by-step explanation:
45 + 16 + 6 = 67 (total bill)
100-67 = 33 (Amount of change she should receive)