Answer:
y = 2x - 25
Explanation:
First find the gradient, we can see it goes through (30,35) and 35,45), and since gradient is found by 'change in y / change in x' we can do: (45-35) / (35-30) = 10/5 = 2
So we know we are looking for an equation with 2x in it.
We have two options: y = 2x - 25 and y = 2x - 75.
Plug in one of the points and see which of the equations works.
Replacing y with 35 and x with 30 in the first equation we have: 35 = 2(30) - 25 = 60 - 25 = 35, this is indeed true.
However if we did the same with the second equation: 35 = 2(30)-75 = 60 - 75 = -15, this is false since 35 does not equal -15, so it can't be the second equation.
In conclusion it must be y = 2x - 25