Felicia Goh's answer to Soni's Primary 5 Maths Singapore question.

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Felicia Goh
Felicia Goh's answer
21 answers (Tutor Details)
1st
General: Use algebra to solve

Part a: Represent your unknowns (in this case, amount of money Mrs Tay have and cost of 1kg of sugar) as constants (in this case, x and y respectively)

Using these constants, come up with 2 equations and solve them simultaneously i.e getting rid of 1 constant through cancelling out gives you the value of the other constant (in this case, x cancels each other out as shown in the green box, allowing u to calculate what y is)

Part b: The link from a to b is subbing value of y back into the equations obtained in part a. U can either substitue back into eqn 1 or eqn 2 as both will give u the same answer. In this case, I chose eqn 1. After substituition, I will get value of x as shown
Felicia Goh
Felicia Goh
5 years ago
Sorry, I forgot to draw the green box. The cancelling out of x is in the eqn1 + eqn2 line
Soni
Soni
5 years ago
Thanks for the help but can you give me the solution but not in algebraic method .