Question

35 minutes before 7:10

Answer 1

10 minutes before would be 7:00, and we still have 25 minutes to subtract from 7:00. there are 60 minutes in 1 hour, so bring 7 down to 6, and then subtract 25 from 60, then put your remaining number in as your minutes place. 60-25 = 35, so then 35 minutes before would be 
6:35

Answer 2

Well we just need to think backwards:)
if we subtract 10 minutes from 35 we get 25
35 - 10 = 25 
now we need to remember that there is 60 minuets in 1 hour
so 60 - 25 = 35 
so since we went backwards its going to be 6 o'clock
add the 35:)
your answer is 6:35:)