Question 881028
Not knowing what is "addition method", you have choice of substitution or elimination.


3(5x-4y)=3*2------multiplying first equation by 3.
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5(-3x+10y)=5(-5)----multiplying second equation by 5.


15x-12y=6
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-15x+50y=-25


62y=-19------------adding corresponding members of each equation.
{{{y=-19/62}}}


You can do similarly to eliminate y to solve for x.,