# Sarin’s family in Kluang part 11 (Math Question)

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The blog postings are about the Singapore Math. The readers can learn from the postings about Solving Singapore Primary School Mathematics. The blog presents the Math Concept, Math Questions with solutions that teaches in Singapore Primary Schools. You or the kids can learn the skills of dealing with Math Modeling, Problem Sum from Lower Primary School to Upper Primary School level after reading the blog postings. This posting is an upper primary school math question on Algebra and Problem Sum.

Read the posting on Sarin learns Symbol, Algebra and Equation in school (Math Concept) to understand the concept of Algebra.

Challenge yourself with the question before look out for the given solution‼!

Upper primary school mathematics question UPQ378

At the Popular Book Co. in Kluang Mall, an eraser cost x cents and a pen cost twice as much. Hairu received some change after paying the
cashier a five-dollar note for 3 pens and 5 erasers. Express the amount of change Hairu received in terms of x.

Solution:

A pen cost twice as much as an earser = 2x cents

He bought 3 pens and 5 erasers

The total cost model

The cost of 5 Erasers = 5x

The cost of 3 pens = 6x

The total cost = 5x + 6x = 11x cents

He paid using a five-dollar note

1 dollar = 100 cents

5 dollar = 5 × 100 = 500 cents

The amount of change Hairu received = (500 – 11x) cents