Help with this im being called a failure

Roaring Zoo has 76 different species of birds. Because of cold weather, only 32 species stayed at the zoo, while the others were transported to the barn until warmer weather returned.

Which equation shows how many species of birds were transported?

b − 32 = 76
b + 32 = 76
b − 76 = 32
b + 76 = 32