1. Mathematics Curriculum Centre Rachel went to the supermarket. She bought some fruit for herself and for her neighbour. However, she forgot to ask for separate bills!

2. Mathematics Curriculum Centre When Rachel checked the price labels on the fruit, she could not read them! - = - _= cents

3. Mathematics Curriculum Centre She knew that she had bought 5 apples and 5 bananas for 90 cents but needed to know the price of each so that she could charge her neighbour accordingly. WW Supermarket 5 apples 5 bananas TOTAL Lm0.90

4. Mathematics Curriculum Centre Luckily, Rachel found yesterday’s bill. 70 cents for 5 apples and 3 bananas. WW Supermarket 5 apples 3 bananas TOTAL Lm0.70 She was charged

5. Mathematics Curriculum Centre Rachel considered herself lucky because she realised that she now knew how to work out the price of an apple and a banana!

6. Mathematics Curriculum Centre Do ? you

7. Mathematics Curriculum Centre WW Supermarket 5 apples 5 bananas TOTAL Lm0.90 Today’s bill WW Supermarket 5 apples 3 bananas TOTAL Lm0.70 Yesterday’s bill

8. Mathematics Curriculum Centre This is what Rachel did. She wrote cents on each apple price label. a

9. Mathematics Curriculum Centre and cents on each banana b price label.

10. Mathematics Curriculum Centre a cents b cents 5 ( a cents) + 5( b cents) = 90 cents

11. Mathematics Curriculum Centre Similarly, yesterday’s bill would be… 5 ( a cents) + 3( b cents) = 70 cents 5 ( a cents) + 5( b cents) = 90 cents In short… 5 a + 5 b = 90 5 a + 3 b = 70

12. Mathematics Curriculum Centre 5 a + 5 b = 90 5 a + 3 b = 70

13. Mathematics Curriculum Centre

14. 5 a + 5 b = 90 5 a + 3 b = 70 She subtracted the bills!! 2 b = 20 b = 10 b cents is 10 cents

15. Mathematics Curriculum Centre b cents is 10 cents, then… 5 a + 5 b = 90 As… is… 5 a + 5 (10) = 90 5 a + 50 = 90 5 a = 40 a = 8 a cents is 8 cents

16. Mathematics Curriculum Centre Now Rachel can charge her neighbour because she found out that an apple costs 8 cents and a banana costs 10 cents!

17. Mathematics Curriculum Centre I want to see the solutions again... I want to see the whole story again…