Question 1210544
I assume you accidentally wrote 42 instead of 4z in the first equation.


{{{system(8y+4z=7,6y-8z=41)}}}


Multiply first by 2 and add parts.
{{{system(16y+8z=14,6y-8z=41)}}}


{{{22y=55}}}


{{{2y=5}}}


{{{highlight(y=5/2)}}}


The other variable, y  try this:
{{{system(3(8y+4z)=3*7,4(6y-8z)=4*41)}}}
You continue.