Let s represent the # of sedans and v the number of vans.
s + v must equal 12 (total number of vehicles owned), so s = 12 - v
(3 passengers per sedan)s + (8 passengers per van)v = 61 passengers total
3(12-v) + 8v = 61, so 36 - 3v + 8v = 61, or 5v = 25. Then v = 5 and s = 7.
The company owns 5 vans and 7 sedans.
