y = x + 3 is the answer
the y-intercept is 3, so the answer should have a "+ 3" in it
when you are trying to determine the gradient (the x), you can use two methods
first method:
picture/sketch the line. If the line is going upwards (from left to right), it's positive. If the line is going downwards (from left to right), it's negative. However, this method only works for this question, you should try using the second method more
second method:
use the formula: (y - y) / (x - x)
So, you use the y from one of the brackets and subtract the y from the other bracket. Then, you put it over the x ,from the same bracket as the first y, and subtract the x from the second bracket. If you are confused, look at the picture. (Sorry for the messy explanation)
