Carson's Rule says:
FM occupied bandwidth =
(2) · (Peak deviation + Highest modulating frequency)
so
FM bw = (2) · (60 kHz + 15 kHz)
FM bw = (2) · (75 kHz)
FM bw = 150 kHz
(I used to eat this stuff for lunch, but it's been almost 40 years. Thanks for taking me back. Those were the good old days.)