Point slope form is:
y − y

= m(x − x

)
Where x

and y

are two known coordinates and m is the slope.
Substitute (4,2) as x and y and 3 as m to find the point-slope form.
y − 2 = 3(x − 4)
Taking it to the next step would be to turn this into slope-intercept form, y=mx+b
y − 2 = 3(x − 4)
y − 2 = 3x − 12
y = 3x − 10