SOLUTION: At present, the sum of the parents' ages is twice the sum of the children's ages. five years ago, the sum of the parents's ages was four times the sum of the children's ages. Fifte
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Question 393625: At present, the sum of the parents' ages is twice the sum of the children's ages. five years ago, the sum of the parents's ages was four times the sum of the children's ages. Fifteen years hence, the sum of the parents' ages will be equal to the sum of the children's ages.How many children are there?
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
At present, the sum of the parents' ages is twice the sum of the children's ages. five years ago, the sum of the parents's ages was four times the sum of the children's ages. Fifteen years hence, the sum of the parents' ages will be equal to the sum of the children's ages.How many children are there?
...
let number of children be x
let sum of childrens' age = y
sum of parents' age = z
..
z=2y
5 years ago
z-10 = 4(y-5x) ( four times their age 5 years ago.)(x children so less 5x)
2y-10=4y-20x
2y-20x=-10
/2
y-10x=-5.....................1
15 years later ( 2 parents so add 30 )
z+30= 15x+y
2y+30=15x+y
15x-y=30......................2
add both
5x=25
/5
Number of children
plug value of x in (1)
15*5-y=30
75-y=30
y=70-30
y=45 sum of childrens' age
...
z= 2y = 90 sum of parents' age
..
m.ananth@hotmail.ca
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