Slope.cpp

// Don't forget to label as C++.
#include <iostream>

// No need to use the std namespace.

int main() {
    // Arrows in the wrong direction, and forgot a newline at the end of the string.
    std::cout << "This is used to find the slope of the line. Please enter two points.\n";
    // No need to use new here.
    float y1, y2, x1, x2; 
    std::cout << "Enter Y 1:";
    std::cin >> y1;
    std::cout << "Enter X 1";
    std::cin >> x1;
    std::cout << "Enter Y 2";
    std::cin >> y2;
    std::cout << "Enter X 2";
    std::cin >> x2;

    // Split long lines.
    std::cout << "The slope of the line that goes through the points (x1, y1) and (x2, y2) is ";
    std::cout << (y1-y2)/(x1-x2) << '\n';
}