1.5x2x4= 12 (kg)

9+ 12=2 1 (kg)

Answer: These two boxes of fruit weigh 2 1 kg.

2.24÷ (9/20-3/10) =160km

A: The total length of this highway is 160 km.

3.(4- 1)+4=7

560÷7=80 km

80x4 = 320km

80x3 = 240km

A: The length of rope A is 320 kilometers, and the length of rope B is 240 kilometers.

4.10x3.14 = 31.4 (cm)

4+ 1=5

3 1.4÷5=6.28 cm

6.28x4=25. 12 (cm)

6.28x 1=6.28 cm

25.12x6.28 =157.7536 (square centimeter)

A: The area of a rectangle is 157.7536 square centimeters.

Language: 1. My son is going to travel far away from home, and my loving mother is sewing clothes for her son at home. What worries her most is that her son won't come back.

On the internet, we can not only learn more knowledge, but also learn about current social affairs.

Math: 1. 12÷84= 1/7

1 1/ 12- 1/7=65/84

65/84÷20%=325/84

A: This number is 325/84.

2. Report: LZ, I won't! This seems to be an Olympic number!

3.20%= 1/5

1- 1/5=4/5

240÷4/5=300 (yuan)

300-240=60 (yuan)

A: Cheap 60 yuan.

4.2/5=40%

40%-30% = 10%

10÷10% =100 (ton)

A: This batch of rice is shipped in 100 tons.

LZ, most of this topic is very simple.