Xiaoli takes a car from Qingdao to her grandmother's home in Huangdao. When she goes there, she passes the ring Bay expressway, the whole journey is about 84 kilometers, and when she returns, she passes the cross sea bridge, the whole journey is about 45 kilometers. The average speed of Xiaoli's car is 1.2 times of that of her return, but it takes 20 minutes more than that of her return 84/1.2x-45/x=20/60 Why 20 / 60?

Xiaoli takes a car from Qingdao to her grandmother's home in Huangdao. When she goes there, she passes the ring Bay expressway, the whole journey is about 84 kilometers, and when she returns, she passes the cross sea bridge, the whole journey is about 45 kilometers. The average speed of Xiaoli's car is 1.2 times of that of her return, but it takes 20 minutes more than that of her return 84/1.2x-45/x=20/60 Why 20 / 60?

That is to turn 20 minutes into hours, so that the units before and after are consistent. 20 minutes = 20 / 60 hours

Xiao Li has lived in her grandmother's house for two consecutive months. How many days may she have lived in her grandmother's house
Determinant!

There are three possibilities: one is 30 + 31 = 61 days
One is 31 + 28 = 59 days
One is 31 + 29 = 60 days
Xiao Li has lived in her grandmother's house for two consecutive months. She may have lived in her grandmother's house for 59, 60 or 61 days. Any one of the three can be written

Xiao Li and her mother went to grandma's house. They took 5 hours by car when they went there. They took 3 hours by train when they came back. The speed of the train was 120 km / h
1. How far is Xiaoli's home from Grandma's? 2. What's the speed of the car per kilometer per hour?

A: 1.120x3 = 360 (km)
2.360 divided by 5 = 72 (km / h)

Aunt Wang's age five years ago is equal to Xiao Li's age seven years later. The sum of Xiao Li's age three years ago and Aunt Wang's age four years ago is 35. How old is Xiao Li this year?

Suppose Xiaoli is x years old, Aunt Wang is x + 5 + 7 years old, x-3 + X + 5 + 7-4 = 35 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 2x = 30, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp