You know that the slope, m=5. You have a point (6,7) as (x,y). The slope-intercept form is y=mx+b. Plug in the number for x,y, and m, and then you would be able to find b using the slope-intercept form. Then rewrite the equation as y=5x+b, which you just found b.
(Here's the first step. 7=5(-6)+b). Find b, and then write the slope-intercept form as y=5x+b.