Lets say the number is x so we can make an equation If is at least 21, that means it has to be greater then or equal to it. 6+5*x>=21 You can subtract 6 from both sides 5*x>=15 Then divide both sides by 5 x>=3 You can conclude that the number is greater then or equal to 3.
As AB and ED are parallel, they have the same slope. This means that since lines that are colllinear with parallel segments are parallel, lines l and m are parallel.
