Multiply the fractions by the others bottom half, both the top and bottom.
1/3 will be multiplied by 4, and 1/4 will be multiplied by 3
1/3 will be 4/12 and 1/4 will be 3/12
Add 4/12 and 3/12 together to get 7/12
The remaining time, 5/12, is the amount of time she spent reading.
