MatLab Question... with 3D plot

linear equations,

-3a + b -c +d + e = 0 b + c + 4e = 0 -3c + 2d + e = 0

Use rref command to find the general solution, express all unknowns with two variables s and t;

Plot 3-D figures to show all unknowns as functions of -1<s<1 and -1<t<1;