SOLUTION: Mary is half her mother's age. Mary's father is 5 years older than her mum. the sum of thier ages is equal to 100. Now how old is Mary, her mum and dad?

Question 828059: Mary is half her mother's age. Mary's father is 5 years older than her mum. the sum of thier ages is equal to 100. Now how old is Mary, her mum and dad?
Answer by TimothyLamb(4379) (Show Source): You can put this solution on YOUR website!
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x = mar
y = mom
z = dad
---
x = y/2
z = y + 5
x + y + z = 100
---
put the system of linear equations into standard form:
---
x - 0.5y = 0
y - z = -5
x + y + z = 100
---
copy and paste the above linear system in standard form into this matrix-method solver:
https://sooeet.com/math/system-of-linear-equations-solver.php
---
solution:
x = mar = 19
y = mom = 38
z = dad = 43
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system matrix
1 -0.5 0
0 1 -1
1 1 1
---
inverse of system matrix
0.8 0.2 0.2
-0.4 0.4 0.4
-0.4 -0.6 0.4
---
determinant of system matrix = 2.5
---
Solve and graph linear equations:
https://sooeet.com/math/linear-equation-solver.php
---
Solve quadratic equations, quadratic formula:
https://sooeet.com/math/quadratic-formula-solver.php
---
Solve systems of linear equations up to 6-equations 6-variables:
https://sooeet.com/math/system-of-linear-equations-solver.php
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