在richTextBox1中随机出了好多加减乘除题想要判断题对错怎么办

public void getEquation()
{
Random r = new Random();

        for (int i = 0; i < 30; i++)
        {

            int n = r.Next(0, 100);
            int m = r.Next(0, 100);
            int num = r.Next(1, 3);
            if (num == 1)
            {
                richTextBox1.AppendText(Convert.ToString(n) + "+" + Convert.ToString(m) + "=" + '\n');
            }
            else
            {
                if (n > m)
                {
                    richTextBox1.AppendText(Convert.ToString(n) + "-" + Convert.ToString(m) + "=" + '\n');
                }
                else
                {
                    richTextBox1.AppendText(Convert.ToString(m) + "-" + Convert.ToString(n) + "=" + '\n');
                }
            }



        }
    }


    private void button1_Click(object sender, EventArgs e)
    {
        getEquation();
    }
}

}

 using System.Text.RegularExpressions;

bool foo(string s)
{
    var m = Regex.Match(s, @"(\d+)([\+\-\*\/])(\d+\)=(\d+)");
        int n1 = int.Parse(m.Groups[1].Value);
        int n2 = int.Parse(m.Groups[3].Value);
        int n3 = int.Parse(m.Groups[4].Value);
        char op = m.Groups[2].Value[0];
        int r = 0;
        switch (op)
        {
            case '+': r = n1 + n2; break;
                case '-' : r = n1 - n2; break;
                case '*' : r = n1 * n2; break;
                case '/' : r = n1 / n2; break;
        }
        return r == n3;
}