Therefore u will subtract 4 from 39 to get the third number which is 35 then subtract 4 from it to get the second number which is 31 then subtract another 4 to get the first number that's 27
1/2 of an hour is 30 minutes That’s 1/4 of the total amount of time they spent in the park So, 30 minutes x 4 would be 120 minutes or 2 hours which means they spent 2 hours at the water park