part A: The expression can be shown as: M – ( P + A + G ). [ Here, M is Mixture of juices, which follows the P = Pineapple juice, A = Apple juice and G = Grape juice ].
part B: So, the mixture of the juices = 0.25 + 0.30 + 0.75 = 1.30. The total amount of juice left after she drank 0.20 liter of the mixture = 1.30 – 0.20 = 1.10 liter is the left in the jar.