Answer:
Common ratio r = 2
Step-by-step explanation:
the fith term of a G.P is 8 times the 2nd term.

Hence, common ratio is 2.
I think 2(2x+20) would work.
there are other ones like: 4(x+10)
Answer:
30
Step-by-step explanation:
180-110=70
70+80=150
180-150=30
For 10 miles, he takes = 85 min
then, 1 mile = 85/10 min.
Now, for 8 miles, it would be 85*8/10 = 68 minutes