Problem: the cost of registration at a professional association meeting was $ 50 per person ; a lunch for registrants only was available for an additional $ 22 per person . if the number of registrants who paid for lunch was 30 more than the number who did not , and if receipts for registration and lunch totaled $ 75,360 , how many people paid just for registration at the meeting ?
Rationale: "hope this might be useful to you . let the number of people who have opted only to register = x now since the registration cost is 50 $ per person , the total amount sums to = 50 x $ as per the information given in the question , the number of registrants who paid for lunch was 30 more than the number who did not . that means , total number of people who registered and paid for lunch = 30 + x . for the people who registered for lunch the cost is 50 $ ( for the event registration ) + 22 $ ( for lunch ) = 72 $ . total amount in this case sums to = 72 ( 30 + x ) = 2160 + 72 x now , total amount received was 75360 . thus , from the above data , 50 x + 2160 + 72 x = 75360 122 x = 75360 - 2160 122 x = 73200 x = 600 . hence the correct ans is c"
annotated_formula: multiply(const_1, const_1)