You are separating a mixture of isopropanol and water. For a$-$c below, plot the feed lines on the $xy$ diagram given below.

a$)$ the feed is $50\%$ isopropanol, and is a vapor$-$liquid mixture that is $33\%$ vapor

b$)$ the feed is $40\%$ isopropanol and is a saturated vapor

c$)$ what is the composition of the azeotrope in this system? $x=y=$