X- 1=( 13-X)+2

X- 1= 13-X+2

2X= 16

X=8

Answer: 8CM long and 5CM wide.

2. There are X big monks and (100-X) little monks.

2X+ 1/2 *( 100-X)= 100

2X+50- 1/2*X= 100

4X-X= 100

X= 100/3

Suppose Xiaohua is now X years old, then Dad is now (25+X) years old.

3*(X+8) +5=(25+X)+8

3X+5+24=X+33

2X=4

X=2

A: Xiaohua is 2 years old now.

5. The topic is incomplete!

You can ask me if you don't understand.