You have the line represented by the equation x-2y=-10 and you are asked to find a parallel line. Two lines are parallel if they have the same slope. In order to find the slope of a line, you should change the original equation to find a new one of the form y=m*x+n. In this case, 2y=x+10, so y=0.5*x +5. Your slope is m=0.5, then you need to find which of the answers have the same slope (note that 0.5=1/2). This would be the 4th answer: y=(1/2)*x-2