we have
y=-3x+12
step 1
Find the y-intercept (value of y when the value of x is equal to zero)
so
For x=0
substitute
y=-3(0)+12
y=12
so
y-intercept is (0,12)
step 2
Find the x-intercept (value of x when the value of y is equal to zero)
For y=0
substitute
0=-3x+12
3x=12
x=4
so
x-intercept is (4,0)