First of all, we know that Emily travels 3/4 of a mile in 4 minutes and 30 seconds (i.e. 9/2 of a minute). So, her current velocity is
of a mile per minute.
At this speed, it takes
![t = (s)/(v) = (3.42)/((1)/(6)) = 3.42\cdot 6 = 20.52](https://img.qammunity.org/2020/formulas/mathematics/middle-school/o7nrq7vj53scfrbtvnjgnu4ibpxyolz47y.png)
minutes to travel 3.42 miles.
Since she left at 8.25, she will arrive at about 8.46, so she's on time for school.