She drove 2 hours at 35 miles per hour for a total of 35 * 2 = 70 miles.
She drove 3 hours at 48 miles per hour for a total of 48 * 3 = 144 miles.
Her total miles were: 70 + 144 = 214.
Her total driving time was 3 + 2 = 5 hours.
Divide her total miles by total time for her average speed:
214 / 5 = 42.8 miles per hour average speed.
Not sure if you need to round the answer or not.