Solve problem 3 on pages 137 and 138 of Math 4 textbook

Guidance to solve problem 3 on pages 137 and 138 of Math 4 textbook

Solution method:
- For part a): In expressions with multiplication and addition, perform multiplication first, addition later
- For part b): In expressions with division and subtraction, perform division first, subtraction later. 

Here's a guide to solving exercise 3 on pages 137 and 138 of the Math 4 textbook. Additionally, this section includes three other exercises: Solution to Exercise 1 on pages 137 and 138 of Math 4 textbook, Solution to Exercise 2 on pages 137 and 138 of Math 4 textbook, and Solution to Exercise 4 on pages 137 and 138 of Math 4 textbook. Let's explore the instructions for solving exercises on pages 137 and 138 of Math 4 to excel in the subject!