I lien ratios for problems like these.
7miles/30 minutes = x miles/105 minutes
Cross multiply
(7miles)(105 minutes) = (30 miles) (x)
735 = 30x
x = 24.5 miles
You can also divide 7 by 30 to get miles/ minute = 0.233 and then multiply that by 105 minutes
0.2333 x 105 = 24.5 miles
