Karel's 7305

Paul's age is 60% of Karel's age. In 15 years, Paul's age will equal 80% of Karel's age. How old is Pavel?

Correct answer:

k =  15
p =  9

Step-by-step explanation:


p=0.60 k
p+15 = 0.80 (k+15)

p=0.60·k
p+15 = 0.80·(k+15)

0.6k-p = 0
0.8k-p = 3

Pivot: Row 1 ↔ Row 2
0.8k-p = 3
0.6k-p = 0

Row 2 - 0.6/0.8 · Row 1 → Row 2
0.8k-p = 3
-0.25p = -2.25


p = -2.25/-0.25 = 9
k = 3+p/0.8 = 3+9/0.8 = 15

k = 15
p = 9

Our linear equations calculator calculates it.



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