So you are going to multiply the fractions by 10,000 to find the amount of money used on that item.
1/2 x 10,000 = 5,000 - FOOD
1/4 x 10,000 = 2,500 - BEVERAGES
1/10 x 10,000 = 1,000 - DECORATIONS
5,000 + 2,500 + 1,000 = 8,500
10,000 - 8,500 = MONEY SPENT ON STAFFING
= 1,500