Ramon paid $3.25 for notepads and $1.80 for markers. what is the total number of items he bought?

Could somebody me with this radical simplification?

In a two-digit number the units' digit is 7 more than the tens' digit. the number with digits reversed is three times as large as the sum of the original number and the two digits. find the number.

If mary had 320 toy cars and she gave her friend 50 cars and then she gave her brother 72 more cars how much toy cars would mary have left ● explain with proper details