Question 656701
let {{{x}}} be Karen's age and {{{y}}} John's age

Karen is eleven years less than four times John's age:

{{{x+11=4y}}}.......1

 If Karen is {{{49}}}, 

{{{x=49}}}..........2....plug it in equation 1

{{{49+11=4y}}}.......1..solve for {{{y}}}

{{{60=4y}}}

{{{60/4=y}}}

{{{15=y}}}

 John is  {{{15}}}- years-old