Family

The family has four children. Ondra is three years older than Matthew, and Karlos 5 years older than the youngest Jane. We know that they have been together for 30 years, and three years ago, they were together for 19 years. Determine how old the children are.

Correct answer:

O =  12
M =  9
K =  7
J =  2

Step-by-step explanation:


O=3+M
K = 5+J
O+M+K+J=30
O-3+M-3+K-3=19

M-O = -3
J-K = -5
J+K+M+O = 30
K+M+O = 28

Pivot: Row 1 ↔ Row 2
J-K = -5
M-O = -3
J+K+M+O = 30
K+M+O = 28

Row 3 - Row 1 → Row 3
J-K = -5
M-O = -3
2K+M+O = 35
K+M+O = 28

Pivot: Row 2 ↔ Row 3
J-K = -5
2K+M+O = 35
M-O = -3
K+M+O = 28

Row 4 - 1/2 · Row 2 → Row 4
J-K = -5
2K+M+O = 35
M-O = -3
0.5M+0.5O = 10.5

Row 4 - 0.5 · Row 3 → Row 4
J-K = -5
2K+M+O = 35
M-O = -3
O = 12


O = 12/1 = 12
M = -3+O = -3+12 = 9
K = 35-M-O/2 = 35-9-12/2 = 7
J = -5+K = -5+7 = 2

J = 2
K = 7
M = 9
O = 12

Our linear equations calculator calculates it.



Did you find an error or inaccuracy? Feel free to write us. Thank you!







Tips for related online calculators
Do you have a system of equations and looking for calculator system of linear equations?
Do you want to convert time units like minutes to seconds?

You need to know the following knowledge to solve this word math problem:

Units of physical quantities:

Grade of the word problem:

Related math problems and questions: