(2) 45÷(7+3)=4.5

(3) (45+3)÷(7-3)= 12

2. Put X pigeons under the tree

(X- 1)÷(X+2+X)= 1/3

The solution is X=5.

There are five pigeons under the tree and seven pigeons on the tree.

6.400(X+Y)= 32

400(X-Y)= 180

7.5×4÷2 = 10

8. According to the meaning of the question: X= 5.5 Y=-1.5 or X=-1.5 Y=5.5.

So: X-Y = 7 or -7.

At the same time, pay attention to the unit and format of application questions and form good habits.

(Advanced Mathematics and Integral Application Research Association) sincerely answers for you,

Have a nice summer vacation. ...