Question 881431
10 year ago the age of A was half as old as B.
{{{((A-10))/((B-10))}}} = {{{1/2}}}
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/B}}} = {{{3/4}}}
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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