15=-4+z/3
+4 +15 = +4 -4 +z/3
cancels the 4 on the right side
19 = z/3
3 x 19 = z/3 x 3
cancels 3 on the right side
I think the answer is z = 57
Tn=n²+3
from 4 to 7....the difference is 3, then from 7 to 12 the difference is 5 and from 12 to 19 the difference is 7
therefore we constantly add 2 to the difference
(132 min)/(12 mi) = (t)/(66 mi)
t = (66 mi)*(132 min)/(12 mi) = 726 min
It will take the bicyclist 726 minutes to travel 66 miles.
