Question 1005487
j and d for ages of JOHN and DAVID



<i>ratio between the ages of John and David is 6:5. </i>
{{{j/d=6/5}}}
{{{j=6d/5}}}



<i>In 7 years time the ratio between their ages will be 7:6</i>
{{{(j+7)/(d+7)=7/6}}}
{{{6(j+7)=7(d+7)}}}
{{{6j+42=7d+49}}}
{{{6j-7d=49-42=7}}}


Substitute for j in the 7-years equation.
{{{6(6d/5)-7d=7}}}
{{{36d/5-7d=7}}}
{{{36d-35d=35}}}
{{{highlight(d=35)}}}


JOHN'S DAVID'S AGE
{{{j=6d/5}}}
{{{j=6*35/5}}}
{{{highlight(j=42)}}}



---
fixed mistake