Answer:
Step-by-step explanation:
[tex]a) -2x-3y=5\\-5x+3y=-40\\-7x=-35\\x=5, y=-5\\\\b)5x+6y=-14\\x-2y=10\\Considering\ equation\ 2,\\3(x-2y)=3(10)\\3x-6y=30\\Hence,\\5x+6y=-14\\3x-6y=30\\8x=16\\x=2, y=-4\\\\c) -3x+3y=21\\-x-5y=-17\\Considering\ equation\ 2,\\3(-x-5y)=3(-17)\\-3x-15y=-51\\Hence, subtracting\ both\ the\ equations\ we\ get,\\-3x+3y=21\\3x+15y=51\\18y=72\\y=4, x=-3[/tex]
d) Let the cost of one group lesson be x and one private lesson be y
[tex]12x+2y=110\\10x+3y=125\\By\ multiplying\ the\ first\ equation\ with\ -1.5\ in\ this\ system\ we\ get,\\-1.5(12x+2y)=-1.5(110)\\-18x-3y=-165\\Hence,\ by\ adding\ both\ the\ equations\ we\ get,\\-18x-3y=-165\\10x+3y=125\\-8x=-40\\x=5,y=25[/tex]
