(I will say 1 - 7 to save time writing each equation)
The correct ones are: 1, 2, 4, 5
Explanation:
In an equation that is in the form y = mx + 3, m represents the gradient (slope) of the line.
Say the gradient of a certain line is 3 and the gradient of another line is -1/3.
If you multiply the two gradients, you get -1. This means that the two lines are perpendicular.
“If the product of the gradient of two lines is -1, the two lines are perpendicular.”
You can see that the gradient of the line in the question is 3/2.
We can easily see that a line perpendicular to it will have the gradient: -1/(3/2) = -1 x (2/3) = -2/3
Look for all the equations that have -2/3 as the gradient and you have the answer, that is 1, 2, 4 and 5.
