# (Filling problem in plotting a figure) How to fill the area between a function and a gridline?

I want to fill the area between the second gridline (blue and count from the left) and the yellow curve as shown in the figure. I used a simple code to illustrate the figure but I have no idea how to fill and represent the specific area. If you have some good suggestions, please share them with me, and thank you in advance.

The code is as follows and I simplify the code of the plot theme part:

Plot[{V = 6*0.3 t^2, V = 3 t - 12*0.3 t^2, V = -3 t + 12*0.3 t^2, V = 3 t},
{t, 0, 5/3}, PlotRange -> {0, Automatic},
GridLines -> {{5/9, 5/6, 5/3}, {0}},
GridLinesStyle -> {{Dashed, Blue}, {Dotted, Blue}},
Filling -> {2 -> Axis}]

• I typed the wrong value for the first gridline which is supposed to be 5/9 but this does not affect the region that needs to be filled. Nov 28, 2020 at 8:03

Plot[{6*0.3 t^2, 3 t - 12*0.3 t^2, -3 t + 12*0.3 t^2, 3 t,
ConditionalExpression[3 t, 8/9 <= t <= 5/3]}, {t, 0, 5/3},
PlotStyle -> {Automatic, Automatic, Automatic, Automatic, None},
PlotRange -> {0, Automatic}, GridLines -> {{8/9, 5/6, 5/3}, {0}},
GridLinesStyle -> {{Dashed, Blue}, {Dotted, Blue}},
Filling -> {2 -> Axis, 5 -> {3}}]


a = Plot[{V = 6*0.3 t^2, V = 3 t - 12*0.3 t^2, V = -3 t + 12*0.3 t^2,