Term 1 Holiday Maths No.6

In parking meters downtown, you can get 15 minutes parking for 50c

Dad put $3.50 into the parking meter at 3.15pm

At what time did the parking meter expire?

Dad put $3.50 into the parking meter at 3.15pm

50c x 4   = $2 = 1h
50c x 3 = $1.50 = 45m
My answer has to be 1:45 because 50c x 4  = $2 and $2 = to 1h. There is $1.50 remaining. I know 1 dollar equals to 30m and 50c equals to 15m. And if we add all of them up together, I will get 1h and 43m.