Please help me and this is very hard for me

I'm assuming you want help with numbers 7 and 8 because multiplication should be easy

so
7.  rico average=15.5mph or 15.5/h
in 2.5 hours how far travel
15.5 in 1 hour
in 2 hours he will travel 2 times 15.5 miles
so in 2.5 hours he will travel 15.5 times 2.5 miles or 38.75

8. use estimation to show reasonable
15.5 can be rounded to 16
16 times 2 is 32
16 times 3 is 48
0.5 is half of 1 so the average is about the answer
(32+48)/2=80/2=40
he will travel about 40 miles (less since you rounded 15.5 up to 16)
so it is reasonable