SOLUTION: 10 year ago the age of A was half as old as B.if the ratio of there present age is 3:4,then the sum of there present age is?

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Question 881431: 10 year ago the age of A was half as old as B.if the ratio of there present age is 3:4,then the sum of there present age is?

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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10 year ago the age of A was half as old as B.
%28%28A-10%29%29%2F%28%28B-10%29%29 = 1%2F2
Cross multiply
B - 10 = 2(A-10)
B - 10 = 2A - 20
B = 2A - 20 + 10
B = 2A - 10
:
if the ratio of there present age is 3:4,
A%2FB = 3%2F4
4A = 3B
Replace B with (2A-10)
4A = 3(2A-10)
4A = 6A - 30
30 = 6A - 4A
30 = 2A
A = 30/2
A = 15 is A's age
then
B = 2(15) - 10
B = 20 yrs is B's age
:
Then the sum of there present age is? 35
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