See, numbers divisible by 15 are in order of 15, 30, 45, 60, so on. We are getting 1 odd then 1 even again odd and even, so on. Therefore we'll have to divide by 2 here.
For multiple of 7 : $\left \lfloor \frac{500}{7} \right \rfloor$ = 71
Odd numbers = $\left \lceil \frac{71}{2} \right \rceil$ = 36