.
This line has an equation
3x + 4y + c = 0, (1)
where "c" is some constant, now unknown.
To find "c", use the condition that y-intercept is 2.
It means that the point (x,y) = (0,2) lies on the line (1), i.e.
3*0 + 4*2 + c = 0,
which gives you the value of c = -8.
Answer. The equation of the straight line under the question is 3x + 4y -8 = 0.
