Question

Which equation represents the line passing through the points (1, 4) and (−2, 13)?

3x + y = 7
3x − y = 7
x − 3y = 7
x + 3y = 7

Answer 1

3x-y=7

Answer 2

You just need to put the point in the equation and check if it states sth. that is true like 1=1 or 5=5 not sth. like 1=3.
The coordinates have the from (X,Y) so you take the first number and plug it in at the x position and the second number belongs in the y spot. If the left side is also 7 you have the right equation.