4. Weights of two friends A and B are in the ratio of 7 : 8. A?s weight increases by 10% and the total weight of A and B increase by 20%. What is the percentageincrease in the B?s weight?
9. In a hostel the rent per room is increased by 20%. If number of rooms in the hostel is also increased by 20% and the hostel is always full, then what is the percentage change in the total collection at the cash counter?