Answer:
43
Step-by-step explanation:
since 43 of them are new, and 15 of them are his favorite, that means that 43+15 58 are new and favorite. In addition, we have one that is both, and since
P(A or B)=P(A)+P(B)-P(A and B)
we have 43+15-1= 57.
100-57 is 43.