This question is about estimating, not getting the exact answer.
Pretend you don’t have a calculator on hand. I’d say an adults ticket is about $58 and a kids ticket is about $42. Or rounding even a bit more, an adult’s ticket is about $60 and a kids about $40.
2 adults + 4 kids: 2 * $60 + 4 * $40 = 280
