Colby adds 1 and 2 over 3 cups of flour to his mixing bowl and then realizes he put in too much. he take 1 over 4 cup of flour back out of the bowl. how much flour did colby's recipe call for

1 and 3/4
takes out 1/4
so 1 and 3/4-1/4
remember that 1 and 3/4=1+3/4
remember that 3/4=1/4+1/4+1/4 so
1 and 3/4-1/4=1+1/4+1/4+1/4-1/4=1+1/4+1/4+(1/4-1/4)=1+1/4+1/4+(0)=1+1/4 +1/4=1+2/4=1+1/2=1 and 1/2
it called for 1 ad 1/2 cup