Sixth grade math, expert help!

105 times 1.2 is one month's property fee, then times 12 is one year's property fee, and finally times 90% is the discount, so the final price is 1360.8 yuan.

Of course, it is 160g, each 1 1.2 yuan. Because 120 grams, each 9 yuan is divided by 9 to get 0.075 yuan per gram; And 160 grams, each 1 1.2 yuan, divided by 1 1.2, get 0.07 yuan per gram. 0.07 is less than 0.075, so I choose to buy 160g, each 1 1.2 yuan.

You can squeeze it 25 times. 5 mm equals 0.5 cm, then the radius is 0.25 cm, then the volume of toothpaste is 0.25×0.25× 1×36=2.25. Divide 2.25 by the square of 0.3, which equals 25. The volume of toothpaste can be represented by a circle. )

S monthly subscription system is more cost-effective.

20 hours is equal to 1200 minutes, so the cost of a timing system is:1200× 0.05+1200× 0.02 = 84 yuan.

S The monthly fee is: 50+ 1200×0.02=74 yuan. So a month is still worthwhile.