Need help for the following questions.

q1. There were 1600 chickens and ducks at first . After 3/4 of chickens and 4/5 of ducks were sold, there were 130 more chickens than ducks in the farm. How many more chickens than ducks were there at first?

Ans: 400

q2. There were 870 children in a stadium at first. After 2/5 of girls and 1/3 of the boys left the stadium, there weee 48 more boys than girls in the stadium. How many boys were there at first?

ans: 450

i got those answers through using algebra and units and parts .

however, I couldn’t get the answers using model. Wonder anyone could use models to solve the questions ?

appreciate the help