$('.quantity_inner .bt_minus').click(function() {
let $input = $(this).parent().find('.quantity');
let count = parseInt($input.val()) - 1;
count = count < 1 ? 1 : count;
$input.val(count);
var price_val = $('.knopka1').data('price');
var curr_val = $('.knopka1').html();
var new_val = parseInt(curr_val)-parseInt(price_val);
$('.knopka1').html(new_val);
});
$('.quantity_inner .bt_minus').click(function() {
let $input = $(this).parent().find('.quantity');
let $val = $('.knopka1');
let count = parseInt($input.val()) - 1;
count = count < 1 ? 1 : count;
let price_val = parseFloat($val.data('price'));
let curr_val = count * price_val;
$input.val(count);
$val.text(curr_val);
});