Problem solving

Multi-step problems with bar models and equations.

Planning a trip

A school trip to the National Zoo needs buses, tickets and food. Each part is a problem to solve. Mathematicians break big problems into smaller steps.

Bar models for comparison

Class A collected ৳134; Class B collected ৳98. The bar model shows the difference: 134 − 98 = 36. Together: 134 + 98 = ৳232.

Writing equations

Write an equation: 3 × ☐ + 15 = 60. Undo: 60 − 15 = 45, then 45 ÷ 3 = 15. Each ticket costs ৳15.

Working systematically

List possibilities in order so you do not miss any. Start with 0 of one kind, then 1, then 2 … There are exactly 3 ways.

Order of operations

Calculations follow an order: brackets, then multiply and divide, then add and subtract. Laws help: 4 × 37 × 25 = 37 × (4 × 25) = 3700. 7 × 13 = 7 × 10 + 7 × 3 (the distributive law).

Two unknowns

When a sentence has two unknowns, there can be many answers. ☐ + △ = 10: 3 + 7, 4 + 6, 5 + 5 … If we also know ☐ − △ = 2, only 6 and 4 work!

What I learnt

I can solve multi-step problems.
I can write and solve simple equations.
I can work systematically.