You’re given that m=7 (slope is 7), so setup the slope-intercept form with that info: y = 7x + b.
Now you need to find b. Plug in (3,11) for x and y, x=3 and y=11.
11 = 7*3 + b
Notice the only variable left is b, so you’ll find b this way.
11 = 21 + b and then subtract 21 from both sides:
11 - 21 = b
-10 = b
Plug that back into the equation and you have y = 7x -10
