October 7, 2019

October 7, 2019

January 5, 2019

November 15, 2018

March 11, 2017

April 11, 2016

###### Recent Posts

###### Featured Posts

*MUST-KNOW PSLE MATH PROBLEM 2*

*MUST-KNOW PSLE MATH PROBLEM 2*

April 11, 2016

Do you know WHEN and HOW to use the Row-Minus-Row Method? This method is used when the question involves several relationships between multiple items and for each relationship a Total is given.

———————————————————————————————————–

Question:

Kyle bought 6 similar pencils, 3 similar books and a file for $78.

1 pencil and 1 book cost $20.

1 pencil and 1 file cost $12.

What was the cost of the file?

———————————————————————————————————–

Solution using the Row-Minus-Row Method:

Given 6p + 3b + 1f = 78 ———–Row 1

Given 1p + 1b = 20

So 3p + 3b = 60 ———– Row 2

Row 1 – Row 2: 3p + 1f = 18 ———— Row 3

Given 1p + 1f = 12

So 3p + 3f = 36 ————- Row 4

Row 4 – Row 3: 2f = 18, so f = 9.

Ans: $9