Antonio is building a shelving unit to hold all of his shoes. A pair of work shoes takes up 2 square feet of space, and a pair of boots occupies 4 square feet. The total amount of shelving space taken up by all the shoes can be at most 66 square feet. Write the inequality in standard form that describes this situation. Use the given numbers and the following variables.

x = the number of pairs of shoes
y = the number of pairs of boots