Answer:
4 visits.
Explanation:
First make an equation to represent the cost of the museum stuff using the formula y=mx+b
y=5x+11 would be the formula because you pay a flat fee of $11 for the membership and $5 for each visit after (x represents visits, y represents total cost)
Now we need to figure out how many visits a bill of $31 would represent.
We plug in 31 for y because y represents the total cost.
31=5x+11
Now solve for x.
Subtract 11 from both sides: 20=5x
Divide each side by 5: 4=x
Since x=4, it means that a bill of $31 would represent four visits.