Answer:
The set of positive integers and zero.
Step-by-step explanation:
[0 1 2 3 4 5 6 7 8 9......∞)
that's the answer man ur welcome btw
Answer:where is the diagram so i could help you
n + f = 15
n + (6) = 15
n = 15 - 6 (opposite side opposite sign)
n = 9
