At the point of sale, the merchant would calculate the amount owed by the customer and indicate the amount, and may prepare an invoice for the customer (which may be a cash register printout), and indicate the options for the customer to make payment.
Performing push-ups works a variety of muscles in your upper body, including specific muscles within your abdomen, chest, shoulders and upper arms. You can vary your technique by placing your hands at different widths to emphasize one area over another.
The major muscle groups used for chin-ups are the latissimus dorsi back muscles and biceps brachii arm muscles, but other back, arm and shoulder muscles assist the lats. Compared to pullups, chin-ups use the pectoral muscles more at the start of the movement and focus the biceps and forearms slightly more.