Answers

2015-07-17T16:15:51+05:30
Let the present ages of A and B be x and y respectively.So,ten years ago:
x-10=(y-10)/2
But,x:y=3:4 so,x=3a and y=4a (a is the constant of proportionality)
so,3a-10=(4a-10)/2
or,3a-10=2a-5
or,a=5
thus present ages of A=15yrs & B=20yrs
total age is 15+20=35 yrs
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2015-07-18T10:12:09+05:30
Let A age's 10 years ago = x years
then the B age's 10 years ago=2x years
given ratios = 3:4 therefore A= 3x,B=4x
therefore present age = (x+ 10) / (2x+10)=3/4
                               = 6x+30=4x+40
                               =6x-4x=40-30
                               =2x=10
                               =x=5
    therefore A= 3x=3(5)=15 B=4x=4(5)=20
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