AAAAHHHH OKAY ILL TRY TO HELP!!!
So the Y intercept is where x =0 so just read that off the graph to get the coordinates (0,8). Then the slope is the same as the gradient so you do change in y/ change in x to get 2/4 = 1/2 or 0.5. Then to work out the equation you already have the gradient so substitute that in to get y = 1/2 x + c and then pick any point from the line ( eg (4,6)) and sub that in to get 6= 1/2 x 4 + c which is 6 = 2 + c so c is 4 so your overall equation is y= 1/2 x + 4 hope this helps :)