Use toothpaste every morning and evening:

( 1÷2)? × 3× 2× 2 = 3 (cubic centimeter)

This toothpaste is estimated to work:

90 ÷ 3 = 30 (days)

This toothpaste is estimated to last for 30 days.

2、

The environmental protection team collects garbage on average;

( 135+22×8)÷( 18+22)

=3 1 1÷40

About 7.8 kilograms

A: The average person in this environmental protection team picks up 7.8 kilograms of garbage.

3、

Unit price of Learning Science per magazine:

135 ÷ (14+16+15) = 3 (yuan)

A small team has to hand in: 14× 3 = 42 (yuan)

The second team should pay: 16× 3 = 48 yuan.

The third team should pay: 15× 3 = 45 yuan.

4、

Retail price of hairtail in this supermarket:

(100-61.6) ÷ 3.2 =12 (yuan/kg)

A: The retail price of hairtail in this supermarket is 12 yuan/kg.

5、

Time required to arrive in Zhengzhou:

542÷ 1 10≈5 (hours)

Plus 1 hour stop on the way, that is, the next day:

20+5+ 1-24=2:00

A: We can arrive in Zhengzhou at 2 o'clock the next day.

6、

Surface area of living room (four walls and top)

5×3.4+(3.4×3+5×3)×2

= 17+50.4

= 67.4 square meters

Excluding the area of doors and windows, * * * has:

67.4- 12 = 55.4 square meters

A * * * needs painting:

55.4× 0.25 = 13.85 (kg)

Answer: A * * * needs 13.85 kg paint.