Ed bought a bottle of fancy mustard that holds 8.5 ounces .edputs about 1/25 of mustard on each hot dog he eats. how much of the mustard is left in the boyle after he eats 7 hot dogs.

Total amt of mustard the bottle has =8.5ounces
if edd puts 1/25 of the mustard on a hot dog.. 1/25 times 8.5 =0.34ounes 
if 0.34ounces of mustard is put on one hot dog
 therefore 7(0.34) is the amt put on 7 hot dogs
7(0.34)= 2.38..( 2.38 ounces is what is used)
 to find what is left, we need to subtract what is used from the original amt in the bottle. 
which is 8.5 - 2.38 =  6.12 ounces is left