Question 994115
The exercise could also be for Algebra 1.


a, Allen's age
j, Jim's age
L, Les's age


Each part of the description can be literally transcribed.
{{{system(a+j+L=157,6(j-20)=7*(a-20),(L+8)=3(a-30))}}}


Use your concepts and skills to simplify the system of equations.
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{{{a+j+L=157}}}, good as it is.
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{{{6j-120=7a-140}}}
{{{7a-140=6j-120}}}
{{{7a-6j-140=-120}}}
{{{7a-6j=20}}}
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{{{L+8=3a-90}}}
{{{3a-90=L+8}}}
{{{3a-L=8+90}}}
{{{3a-L=98}}}



The equivalent linear system is
{{{highlight(system(a+j+L=157,7a-6j+0*L=20,3a+0*j-L=98))}}}


Are you good with a system like this or do you still need help?