Adding new row after button click and set value to text box

i have designed a main form with textbox and button(when button is clicked modal popup must open).inside modal popup there are two text boxes and a submit button.i am performing subtraction operation inside modal popup. after submit button is clicked inside modal popup,modal popup is closed and result must be shown in textbox which is on the main form and also a new row will be added automatically with a button and a textbox(with out effecting previous textbox result).the problem is when submit button is clicked inside popup, the result is showing same in main form textbox and also added row text box(i.e effecting the previous row).can any one solve my problem here is the code here is js fiddle codeenter code here https://jsfiddle.net/c7uL0pnw/1/