A cord 90 cm long was cut into two parts so that one part was 20 cm longer than the other. Find the length of each part.

The problem can be solved in two ways.
Method 1:
If we denote one part of the cord as x, then the second part will be (x + 20). Let’s compose and solve the equation:
x + (x + 20) = 90
x + x + 20 = 2x + 20 = 90
2x = 90 – 20 = 70
x = 70: 2 = 35 meters
35 meters is the length of one piece of the cord. Now we will find the length of the second part of the cord.
90 – 35 = 55 meters
The second part will be 55 meters long.

Method 2:
To solve in the second way, we compose an expression and find the length of one part of the cord.
(90 – 20): 2 = 35 m
Then we find the length of the second part of the cord.
90 – 35 = 55 m
Let’s check the result:
35 + 55 = 90 meters
Answer: The length of the first part of the cord is 35 meters, the second part of the cord is 55 meters.