4 1/4 lbs of onions = 1llb
so there are 4 x 3 servings = 12 servings in 1 lb
6 servings in 1/2 lb
total of 12+6= 18 servings
you can also use ratio and proportion
converted to decimals to eliminate fractions
,25/3= 1.5/x
cross multiply
.25x= 4.5
x=18
hope this helps