Question 352513
Let t = the amount of time the car would catch up with the bus.  The car took off 15 minutes, or 1/4 of an hour after the bus.  Therefore the amount of time before the car catches up with the bus is {{{t-1/4}}}.  From the formula
{{{D = RT}}} (or distance = rate x time), 
{{{45*(t - 1/4)=30*t}}},
{{{45*t-45/4 = 30*t}}},
{{{15*t = 45/4}}},
{{{t = 3/4}}}.
So the car would catch up with the bus after 3/4 hr, or 45 minutes.