How many quarter horses? The rent-a-stall horse barn has stalls for 1000 horses. Forty percent of the stalls are for ponies. On Tuesday, there were 200 ponies and a bunch of quarter horses at the horse barn. The horse barn was 75 percent full. How many quarter horses were in the stalls?

Assuming the 40% number is irrelevant

$200 + h = .75 \times 1000$

$h=550$