Use a simple method to calculate the scores of the following questions Two nines minus seven sixteen times two nines Two fifths by four times three fourths One half by one-fifth plus one-third by one-half Four fifths by seven ninths by five eighties Five sixths by five nines plus five nines by one sixth Five out of seven by sixteen by twenty-one out of five

Use a simple method to calculate the scores of the following questions Two nines minus seven sixteen times two nines Two fifths by four times three fourths One half by one-fifth plus one-third by one-half Four fifths by seven ninths by five eighties Five sixths by five nines plus five nines by one sixth Five out of seven by sixteen by twenty-one out of five

Hello!
Two nines minus seven sixteen times two nines
=2/9x(1-7/16)
=2/9x9/16
=1/8
Two fifths by four times three fourths
=2/5x3
=6/5
One half by one-fifth plus one-third by one-half
=1/2x(1/15+1/3)
=1/2x2/5
=1/5
Four fifths by seven ninths by five eighties
=(4/5x5/8)x7/9
=1/2x7/9
=7/18
Five sixths by five nines plus five nines by one sixth
=5/9x(5/6+1/6)
=5/9x1
=5/9
Five out of seven by sixteen by twenty-one out of five
=(5/7x21/5)x16
=3x16
=48
If you don't understand this question, you can ask. If you are satisfied, please click "adopt as satisfactory answer"
If you have any other questions, please take this question and send it to me. Please understand
I wish you progress in your study!

The application of cylinder in mathematics volume 2 of grade 6 of primary school
A piece of tin chimney is 1.6 meters long and 0.2 meters in diameter. How many square meters of tin should be used to make such a chimney

0.2 * 3.14 * 1.6 * 5 = 5.024 (M2)

In a city, the standard of water consumption for residents has been formulated. The water charge per cubic meter of standard water is 1.40 yuan, and the water charge per cubic meter of excessive water is increased by 100%. There are three Xiaoming family members. They use 15 cubic meters of water in May, and pay 25.2 yuan. What is the maximum standard of water consumption per month for a family of three in the city? (hint: we can think about it by hypothesis replacement method)

25.2-1.40*15=4.2
4.2/1.40=3
15-3=12
A: the highest water consumption standard of a family of three in the city is 12 cubic meters per month