Chapter 1 - Graphs - 1.3 Lines - 1.3 Assess Your Understanding - Page 31: 63

$y=2x.$

If two lines are parallel then their slopes must be equal. We know that if the slope of a line is $m$ and it contains $P_1(x_1,y_1)$, then its equation is: $y-y_1=m(x-x_1).$ It is parallel to $2x-y=-2$, which is $y=2x+2$,then its slope is $m=2$. Hence here: $y-0=2(x-0)\\y=2x.$