Their speeds are ' s ' and ' s+7 ' .
Since Joon is decreasing the size of the distance between them from one end,
and Gerace is decreasing it from the other end, the distance between them is
shrinking, and they meet when the SUM of their distances is 174 miles.
The sum of their speeds is (s) + (s+7) = (2s+7) m/h
They meet after driving for 2 hours, so
(2h) x (2s+7) m/h = 174 miles
Eliminate the parentheses: (4s + 14) = 174
Subtract 14 from each side: 4s = 160
Divide each side by 4 : s = 40
Their speeds are 40 mph and 47 mph .
Check:
40 mph for 2 hours = 80 miles
47 mph for 2 hours = 94 miles
80 + 94 = 174 miles yay !
