Mary Wanted to Buy a Mixture of Nuts to Put

Mary wanted to buy a mixture of nuts to put on the tables at her daughter's wedding, so she went to the bulk food store, where she bought 36 lb of three types of nuts. She bought cashews for $2.97 per pound, almonds for $2.47 per pound, and pecans for $1.26 per pound, and her total before taxes was $78.9. The number of pounds of almonds and pecans was the same as three times the number of cashews. How much of each type of nut did Mary buy?

A) 7 lb of cashews, 15 lb of almonds, 14 lb of pecans
B) 10 lb of cashews, 14 lb of almonds, 12 lb of pecans
C) 9 lb of cashews, 16 lb of almonds, 11 lb of pecans
D) 9 lb of cashews, 15 lb of almonds, 12 lb of pecans