Question 1151467

let Lyn's father age be {{{x}}} and Lyn's age {{{y}}}


if Lyn's father is {{{4}}} times as old as Lyn, we have

{{{x=4y}}}...........eq.1

if {{{five}}} years ago the father was {{{7}}} times as old as Lyn, we have

{{{x-5=7(y-5)}}}.......eq.2

substitute {{{x}}} from eq.1


{{{4y-5=7(y-5)}}}.......eq.2......solve for {{{y}}}

{{{4y-5=7y-35}}}

{{{35-5=7y-4y}}}

{{{30=3y}}}

{{{y=10}}}

 
 Lyn is {{{10}}} years old now