Question 161532
.06x+.15*2=.12(x+2)
.06x+.3=.12x+.24
.06x-.12x=.24-.3
-.06x=-.06
x=-.06/-.06
x=1 quart of 6% butterfat is used. 
Proof:
.06*1+.15*2=.12(1+2)
.06+.3=.12*3
.36=.36