Chapter 4 - Section 4.3 - Solving Systems of Linear Equations by Addition - Exercise Set - Page 308: 42

$(0.75, -1.5)$

$0.04x - 0.05y = 0.105$ $0.2x - 0.6y = 1.05$ Multiply the first equation by 1000 and the second equation by 100. $40x-50y=105$ $20x-60y=105$ Multiply the second equation by $-2$. $40x-50y=105$ $-40x+120y=-210$ Add both equations. $70y=-105$ $y=-1.5$ Solve for $x$. $40x-50y=105$ $40x-50(-1.5)=105$ $40x+75=105$ $40x=30$ $x=0.75$ $x=0.75; y=-1.5$ $(0.75, -1.5)$