Edit in JSFiddle

.input_fields_wrap{
max-width: 350px;
}
.input_fields_wrap input[type=text]{
 width:100%;
 margin:2px 0;
}
<button type="button" class="add_field_button">Add Field</button>
<button type="button" class="remove_field_button">Remove Field</button>
<div class="input_fields_wrap">
<input type="text" name="answer[]" class="field-long" />
<input type="text" name="answer[]" class="field-long" />
<input type="text" name="answer[]" class="field-long" />
</div>
var max_fields      = 10;
var wrapper         = $(".input_fields_wrap"); 
var add_button      = $(".add_field_button");
var remove_button   = $(".remove_field_button");

$(add_button).click(function(e){
	e.preventDefault();
	var total_fields = wrapper[0].childNodes.length;
	if(total_fields < max_fields){
		$(wrapper).append('<input type="text" name="answer[]" class="field-long" />');
	}
});
$(remove_button).click(function(e){
	e.preventDefault();
	var total_fields = wrapper[0].childNodes.length;
	if(total_fields>1){
		wrapper[0].childNodes[total_fields-1].remove();
	}
});