function validateThis(){
    var agreeOBJ = document.getElementById("agreed");
    if(agreeOBJ.checked) return true;
    alert("Please check the box above.");
    return false;    
}
function changedImage(){
    var agreeOBJ = document.getElementById("agreed");
    var falseOBJ = document.getElementById("cartFalse");
    var trueOBJ = document.getElementById("cartTrue");
    if(agreeOBJ.checked){
        trueOBJ.style.display="block";
        falseOBJ.style.display="none";
    }
    else{
        trueOBJ.style.display="none";
        falseOBJ.style.display="block";
    }
}