# Sarin and his mother Part 3 (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 presenting the Math Concept, the Math Questions with solutions that teaches in Singapore Primary Schools. You or the kids can learn the skills to deal with the Math Modeling, the Math Problem Solving and the 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 looking out for the given solution‼

Upper primary school mathematics question UPQ413

Sarin is 5 years old. His mother is 33 years old. In how many years’ time will his mother be thrice as old as he?

Solution:

After Y year, Sarin’s mother is thrice as old as Sarin.

The model

From the model

2Y = 33 – 5 – 5 – 5 = 18

Y = 9

After 9 years’ time his mother will be thrice as old as him.

Alternative Solution(1):

By Algebra and equation:

Set after Y years, Sarin’s mother age will be 3 times of Sarin’s age

Sarin’s age after Y years = Y + 5

Sarin’s mother age after Y years = Y + 33

3 times of Sarin’s age = 3 (Y + 5) = 3Y + 15

Therefore,

3Y + 15 = Y + 33

2Y = 18

Y = 9

After 9 years’ time his mother will be thrice as old as him.