Simplifying code

1

I’m working on a multiple choice game and the AS I’ve written so far works, but I know it can be made simpler by using arrays…
can someone please give me a tip on how to shorten this?
thanx!

(cb01…cb18 are checkboxes and marks and wrong are counters)

send_btn.onRelease = function() {

marks = 0;
wrong = 0;

    if(cb01.selected == true) {
        marks = (marks+1);
    }
    if(cb02.selected == true) {
        marks = (marks+1);
    }
    if(cb03.selected == true) {
        marks = (marks+1);
    }
    if(cb04.selected == true) {
        marks = (marks+1);
    }
    if(cb05.selected == true) {
        marks = (marks+1);
    }
    if(cb06.selected == true) {
        wrong = (wrong+1);
    }
    if(cb07.selected == true) {
        wrong = (wrong+1);
    }
    if(cb08.selected == true) {
        marks = (marks+1);
    }
    if(cb09.selected == true) {
        wrong = (wrong+1);
    }
    if(cb10.selected == true) {
        marks = (marks+1);
    }
    if(cb11.selected == true) {
        marks = (marks+1);
    }
    if(cb12.selected == true) {
        wrong = (wrong+1);
    }
    if(cb13.selected == true) {
        marks = (marks+1);
    }
    if(cb14.selected == true) {
        wrong = (wrong+1);
    }
    if(cb15.selected == true) {
        marks = (marks+1);
    }
    if(cb16.selected == true) {
        marks = (marks+1);
    }
    if(cb17.selected == true) {
        wrong = (wrong+1);
    }
    if(cb18.selected == true) {
        marks = (marks+1);
    }
    if((marks+wrong) < 8) {
        rule1_txt.text = "";
        rule2_txt.text = "";
        rule3_txt.text = "Bitte wählen Sie acht";
        rule4_txt.text = "Produkte!";
    }
    else if((marks+wrong) > 8) {
        rule1_txt.text = "";
        rule2_txt.text = "";
        rule3_txt.text = "Bitte wählen Sie nur";
        rule4_txt.text = "acht Produkte!";
    }
    else if((marks+wrong) == 8) {
        if(marks == 8) {
            getURL(URL_correct, "_self");
        }
        else
        {
            getURL(URL_incorrect, "_self");
        }
    }

trace(marks);
trace(wrong);

}