Answer: He bought 5 dozen donuts
Explanation:
d + b = 12 where d is the number of donuts and b is the number of bagels.
9d + 8b= 101 now solve the two equations using the elimination method
-9d - 9b =-108
9d + 8b = 101
-1b = -7
b = 7
9d + 8(7)= 101
9d + 57 = 101
9d = 45
d= 5