Question 1060312
As I understand this:
The sum of son and fathers age is 74 years.
s + f = 74 
f = (74-s); use this form for substitution
the ratio of their age was 7:2, 10 years ago.
{{{((f-10))/((s-10))}}} = {{{7/2}}}
Cross multiply
7(s-10) = 2(f-10)
7s - 70 = 2f - 20
7s = 2f - 20 + 70
7s - 2f = 50
replace f with (74-s)
7s - 2(74-s) = 50
7s - 148 + 2s = 50
9s = 50 + 148
9s = 198
s = 198/9
s = 22 yrs if the son's age
and
74 - 22 = 52 is Dad's age
:
what is the ratio of their age after 10 year?
add 10 yrs to their ages
{{{62/32}}} = {{{31/16}}}. a Ratio of  31:16
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