overheads+variance

The standard fixed production OAR in a factory is $20/machine hour. 1,760 machine hours
were worked during the period in which the fixed production overhead variances included:
Capacity $3,600 Fav
Volume $2,400 Adv
What were the budgeted machine hours?
a. 1,580
b. 1,880
c. 1,940
d. 1,640

Respected Sir,
when I use the capacity variance and work my way backwards the ans I get is 1580:
capacity variance =3600F so we’ve got more hours than expected.
with std. OAR of $20 per hr.
we’ve got 3600/20=180 more hours
so our budgeted hrs. =actual hours of 1760-180=1580 hrs.

then I tried using the volume variance, and work my way backwards the ans I get is 1880:
volume variance =2400A so we’ve produced less hours than expected.
with std. OAR of $20 per hr.
we’ve got 2400/20=120 less hours
so our budgeted hrs. =actual hours of 1760+120=1880 hrs.

To say the least, I’m perplexed. Where have I gone wrong? Please sort me out Sir.