The following four 4 equations are needed to be plotted as CONTOUR lines on the axes space (C, T) where C is the horizontal axis, and T is the vertical axis.

Contour lines for each equation should be between 6 and 8.

in total there should be five (5) plots, one for each equation, and the fifth which, is the most important, a plot with all the four equations are imposed on the same axes system (C, T)

M = (C) * ( 2*T + 0.028)                                                         (eq. 1)

P1 = (0.1237) * (C^(-4/3)) * (T) * ((T+1)^(1/3))                      (eq. 2)

P2 = (0.003) * (C) * (T+1)                                                       (eq. 3)

P3 = 4 * (C^2) * (T) * (T+1)                                                    (eq 4)

M contour lines to be dashed lines, while P1, P2 and P3 to be solid lines in different colours.

No area filling, and no labeling are required.