Which is an equation of line with slopr 4 and y intercept of - 3

Any equation in the form y=mx+b with a slope of 4 must have m=4 and to have a y intercept of - 3, b=-3. You can put that together to make y=4x-3.

The reason the y intercept is - 3 when b=-3 is because y intercept signifies the value of y when x=0. And when x=0, mx=0, so all you have left is y=b. Slope is just how quickly y increases compared to x.

The equation will be

Y = 4x-3