Tuesday, September 27, 2011

Solution to Worksheet 9-Challenge Yourself Question 2

Let the units digit be x
Thus, the tens digit is x+5
2[10(x+5)+x]-128=10(x)+(x+5)
2(10x+50+x)=10x+x+5+128
20x+100+2x=11x+133
22x+100=11x+133
11x=33
x=3
3+5=8(tens digit)
Thus, the original number is 83.
Done by LiuGuoJun, Alvin Tang and Isaac Lim. 

1 comment:

  1. Quite complicated but fairly understandable. Consider expanding before making it into a number statement to avoid confusion. Great job!

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