How to use java to find the X-intercept of a slope?

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Java

mathematics

I've never used Java, one of my programming friends gave me this to try and get used to Java.

He gave me the test.java file along with some pointers for making the line class. However, I still don't know how to get the slope or y_int. I assume for vert I continue to use a Boolean and if/else statement but I am a bit lost.

this is the Test.java:

public class Test {
public static void main(String [] args){
    Line line1 = new Line(0,1);
    Line line2 = new Line(0.5,2);
    Line line3 = new Line(1);
    System.out.println("The slope of "+ "line is ")+line1.getSlope();
    System.out.println("It is"+line3.vert)+ "that line3 is vertical"();
    System.out.println("the slope of line3")+ "is "+line3.getSlope();
}
}

this is the Line.java Class

public class Line {

    public class Line {

    public double slope;
    public double y_int;
    public double x_int;
    public boolean vert;

    public Line(double slope, double y_int){
        this.slope = slope;
        this.y_int = y_int;
        vert = false;
    }

    public Line(double x_int) {
        slope = Double.NaN;
        y_int = Double.NaN;
        vert = true;
        this.x_int = x_int;
    }

    public double getSlope() {
        return slope;
    }

    public double getY_int() {
        return y_int;
    }

    public boolean isVert() {
        return vert;
    }
}

What I have tried:

I suppose it comes down to me not being the best at math. I obviously understand the slope formula but translating to code has proven difficult.