To write an equation for the first situation, you need to determine which factors can be changed. The bus will not change since you can have multiple people in one. The ticket to the museum is per person. This will change depending on how many people there are.
450 + 15.75x
For the second equation, you need to find how many people can go for it the cost to be equal to $40 per person. Set the equation equal to $40 per person and solve.
