Find a · b. |a| = 4, |b| = 7, the angle between a and b is 2π/3

What does it mean by solve the exponential equation for x?

Witch represents the inverse of the function f(x)=1/4x-12

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?