The equation 10x +12=72.00 shows the total cost for x people attending a concert. how many people attended the concert

How do i do this activity, is appreciated

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)

Sarah took the advertising department from her company on a round trip to meet with a potential client. including sarah a total of 11 people took the trip. she was able to purchase coach tickets for $280 and first class tickets for $1280. she used her total budget for airfare for the trip, which was $6080. how many first class tickets did she buy? how many coach tickets did she buy?