1. The school bought 10 boxes of chalk. 250 boxes have been used, and there are 550 boxes left. How many cases are there in each case on average?

There are 200 students in grade four. During extracurricular activities, 80 girls went to jump rope. The boys are divided into five groups to play football. How many people are in each group?

3. The canteen sent 150 kg of rice, which was 30 kg less than the flour. How many kilograms of flour does the canteen send?

There are 52 peach trees and 6 rows of pear trees in the orchard, and there are 20 more pear trees than peach trees. How many pear trees are there in each row on average?

5. The area of a triangular land is 840 square meters, the bottom is 140 meters, and the height is how many meters?

way

1, estimation method: an introductory method when you are just learning to solve equations. Estimate the solution of the equation directly, and then substitute it into the original equation for verification.

2. Apply the properties of the equation to solve the equation.

3. Merge similar terms: transform the equation into a monomial.

4. Move the term: move the unknown term to the left and the constant term to the right.

5. Delete brackets: Use the rule of deleting brackets to delete brackets from the equation.