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First one
480 sandwiches
3/8 are tuna = (3/8) ( 480) = 180 are tuna
35% are beef = .35 (480) = 168 are beef
So 480 - (180 + 168) = 132 are either ham or cheese
Ham : Cheese = 5 : 6
So (5/11) of the remaining sandwiches are ham = (5/11) * (132) = 60
Second one....a little difficult
Circle : Stall = 2 : 5
If the Circle seats 528 people, the Stall will seat 5/2 times this = 528 (5/2) = 1320
But only (2/3) of these were occupied = 1320 (2/3) = 880 seats
So....the percentage of total occupancy =
[ 880 + 528 ] 1408
___________ = ______ ≈ 76%
[ 1320 + 528] 1848