Michael V. answered 03/13/19
Retired military service member with 10+ years teaching experience
John,
This problem uses the formula of distance = rate (speed) x time. In this case, since Ian and Andrew leave from the same location and are traveling the same direction, the distance they both travel will be the same (equal to each other)
Distance = Rate x Time
Ian: 42T 42 T
Andrew: 63T-2079 63 T-33
Set the equation to show that the distances are equal and solve for T.
42T=63T-2079
-63T -63T
-21T=-2079
/-21 /-21
T=99 hours