Youngest 4808

Peter, Leo, and Ivo are siblings. Peter is three times older than Leo, and Leo is three times younger than Ivo. They are 28 years old together.
How many years is the youngest of them?

Correct answer:

l =  4

Step-by-step explanation:


p = 3l
l = i/3
p+i+l=28

p = 3·l
l = i/3
p+i+l=28

3l-p = 0
i-3l = 0
i+l+p = 28

Pivot: Row 1 ↔ Row 2
i-3l = 0
3l-p = 0
i+l+p = 28

Row 3 - Row 1 → Row 3
i-3l = 0
3l-p = 0
4l+p = 28

Pivot: Row 2 ↔ Row 3
i-3l = 0
4l+p = 28
3l-p = 0

Row 3 - 3/4 · Row 2 → Row 3
i-3l = 0
4l+p = 28
-1.75p = -21


p = -21/-1.75 = 12
l = 28-p/4 = 28-12/4 = 4
i = 0+3l = 0+3 · 4 = 12

i = 12
l = 4
p = 12

Our linear equations calculator calculates it.



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