If l, m, and n are parallel, solve for x

How do you use the additive inverse to evaluate an expression that uses subtraction in a full sentence

Aswim teacher sells lesson packages. the best deal has the highest ratio of lessons to total cost.swim lesson packagesnumber of lessons total cost$10$4010 1 $8015$80which package is the best deal? l lesson for $105 lessons for $4010 lessons for $8015 lessons for $80mark this and returnsave and exit

X+y=-4 x-y=2 use elimination with adding and subtraction