Usually involves a basic "increase by" or "decrease by" scenario.

In the 2nd-grade mathematics textbook by (School 2100 program), pages 4 and 5 of Part 1 focus on reviewing 1st-grade material, specifically "Numbers from 1 to 20" and basic operations. Page 4: Reviewing Numbers 1–20

Example Task: "There were 12 red cars and 5 blue cars in the parking lot. How many cars were there in total?"

Page 5 transitions into solving simple word problems and expressions.