Chapter 3 Linear Systems and Matrices - 3.2 Solve Linear Systems Algebraically - 3.2 Exercises - Skill Practice - Page 165: 51

$x=-\frac{1}{9}$ and $y=6$

$7y+18xy=30$ $13y-18xy=90$ _________________ $7y=30$ $13y=90$ _________________ $20y=120$ $y=\frac{120}{20}$ $y=6$ when $y=6$... $7(6)+18(6)x=30$ $108x+42=30$ $108x=-12$ $x=-\frac{12}{108}$ $x=-\frac{1}{9}$