Atkinson, inc., manufactures products a, b, and c from a common process. joint costs were $129,960. additional information is as follows: if processed further product units produced sales value at split-off sales value additional costs a 7,200 $ 47,200 $ 65,200 $ 4,800 b 6,600 57,750 74,250 9,900 c 3,300 39,600 49,500 13,200 17,100 $ 144,550 $ 188,950 $ 27,900 assuming that joint production costs are allocated using the physical quantities method (units produced), what were the costs allocated to product a?