Variance - find actual fixed overhead expenditure & actual production

A company operates a standard marginal costing system. Last month actual fixed overhead expenditure was 2% below budget and the fixed overhead expenditure variance was $1250. What was the actual fixed overhead expenditure for the last month? A.61250, B.62475 C.62500 D.63750 can please advise whether I can use the answer to find the correct answer ? See my working : I use the answer C = 62500 - 2% = 61250 ( correct answer is A) to get actual overhead ? but answer is correct. another question : The standard direct material cost for a product is $50 / unit (12.5kg at $4/kg).Last month the actual amount paid for 45600kg of material purchased and used was $173,280 and the direct material usage variance was $15200 adverse. What was the actual production last month? A.3344 units B.3520 units C.3952 units D.4160 units my working : I take answer A . 3344 units x 12.5/kg = 41800 kg less actual used = 45600 kg variance usage 3800 kg x $4/kg = $15,200 adverse please advise can I take the answer to test one by one until I get $15,200 ? thank you.