After mom's money goes to 32 yuan first, the total amount of money left by mom and dad is 172-32= 140 yuan. If dad spends another 4/9 of his money, he will leave 5/9, which is exactly the same as the money left by mom, indicating that mom used it, but when dad is useless, the ratio of mom and dad's money is 1: (.

5+9= 14 copies

Dad has 140×9/ 14=90 yuan (mom has 172-90=82 yuan).