#include "stdio.h"

float slope(float rise, float run)
{
        /*declaring variables*/
        int x1;
        int y1;
        int x2;
        int y2;

        /*equation to find slope of line, where m=slope*/
        rise=y2-y1;
        run=x2-x1;
        return rise/run;
}

float intercept(float y1, float slope, float x1)
{
        /*equation of the line*/
        return y1-(slope*x1);
}

int y_coordinate(float slope, float x, float intercept)
{
        /*equation to find the y coordinate*/
        return slope*x+intercept;
}

int x_coordinate(float y, float intercept, float slope)
{
        /*equation to find the x coordinate*/
        return (y-intercept)/slope;
}

int main()
{
        /*declaring variables*/
        int x1;
        int y1;
        int x2;
        int y2;
        float x;
        float y;
        float intercept;
        float slope;
        float rise;
        float run;
        int a = 1;

        while (a != 0)
        {

                /*user input*/
                printf("x1: ");
                scanf("%d", &x1);
                printf("y1: ");
                       scanf("%d", &y1);
                       printf("x2: ");
                scanf("%d", &x2);
                printf("y2: ");
                scanf("%d", &y2);

                /*using previous functions to calculate the equation of the line*/
                y = slope(rise, run)*x + intercept(y1, slope, x1);

                /*print equation of the line*/
                       printf("y = %fx + %f\n", slope, intercept);

                /*user input for x value*/
                printf("Enter a value for x: ");
                scanf("%f", &x);

                /*using previous function to find y-intercept*/
                y= y_coordinate(slope, x, intercept);

                /*print y coordinate*/
                printf("y = %f\n", y);

                /*user input for y value*/
                printf("Enter a value for y: ");
                scanf("%f", &y);

                /*using previous function to find x-intercept*/
                x= x_coordinate(y, intercept, slope);

                /*print x cooridinate*/
                printf("x = %f\n", x);

                /*user input to decide whether or not to continue*/
                printf("Enter 0 to quit, 1 to continue: ");
                scanf("%d", &a);
        }

        return 0;
}