The x-intercept is found by substituting y = 0. Solve.
The y-intercept is found by substituting x = 0. Solve.
This is a very inportant concept that you should pound into your brain.
x-intercepts look like this (a,0)
y-intercepts look like this (0,b)
More still. The form of the equation that you ahve presented is the "Slope-Intercept" form. It means the y-interecept is staring at you.
y=4x+3 ==> y-intercept is (0,3)
The x-intercept is a hair trickier.