Question

Ali hops on his 3 wheeler and heads off at 12 mph. Two hours later, Fatimah chases after him on a moped at 18 mph. How far will Ali get before Fatimah overtakes him? Write the system equations.

Answer 1

Answer: 72 miles.

Explanation:

We know the relationship:

Distance = speed*time.

Then we can write the equation for distance as a function of time for Ali as:

A(t) = 12mph*t

where t is time in hours.

Fatimah's equation will be:

F(t) = 18mph*(t - 2h)

where the -2h appears because she starts two hours after Ali.

Fatimah will overtake Ali when F(t) = A(t) (their positions are the same)

Then we need to solve:

12mph*t = 18mph*(t - 2h)

12mph*t = 18mph*t - 18mph*2h

12mph*t = 18mph*t - 36 mi

36 mi = (18mph - 12mph)*t

36mi = 6mph*t

36mi/6mph = t

6h = t

So Ali travels for 6 hours before he gets overtaken, then the total distance that Ali travels is:

A(6h) = 12mph*6h = 72 mi