Question 1153494


let Jack’s age be {{{x}}}, 

 Jill’s age {{{y}}}

if three times Jack’s age +{{{2}}} times Jill’s age equals {{{64}}}, we have

{{{3x+2y=64}}}......eq.1

if Jack is also two times Jill’s age, then Jack is: 

{{{x=2y}}}.....eq.2

go to 

{{{3x+2y=64}}}......eq.1, substitute {{{x}}}

{{{3*2y+2y=64}}}......solve for {{{y}}}

{{{6y+2y=64}}}

{{{8y=64}}}

{{{y=64/8}}}

{{{y= 8}}}

go to eq.2

{{{x=2y}}}.....eq.2, substitute {{{y}}}

{{{x=2*8}}}

{{{x=16}}}

so, Jack is {{{16}}} years old