Question 206585
.15x+.01(5-x)=.03*5
.15x+.05-.01x=.15
.14x=.15-.05
.14x=-.1
x=.1/.14 
x=.714 liters of 15% milk is used.
5-.714=4.286 liters of 1% milk is used.
30/7 1 is the ratio.