Explanation:
Time spent for chemistry assignment=2/5 hour
=2/5 × 60 = 24
= 24 minutes
Time spent for history assignment =1/4 hour
=1/4 × 60 =15
=15 minutes
Total amount of time spent= 24 + 15
=39 minutes
Answer in fraction = 39/60= 13/20
Final answer is = 13/ 20