float loan, rate, payment;
    printf("Enter amount of loan: ");
    scanf("%f", &loan);
    printf("rate: ");
    scanf("%f", &rate);
    printf("payment: ");
    scanf("%f", &payment);

    rate = rate * 0.01 / 12;
    loan = loan + loan * rate - payment;
    printf("first payment: $%.2f\n", loan);
    loan = loan + loan * rate - payment;
    printf("second $%.2f\n", loan);
    loan = loan + loan * rate - payment;
    printf("third $%.2f\n", loan);