$4-$ For the two models below, provide the standard for of the linear programs, i$.$e$.,$ in the form mincx s$.$t$.$ Ax$=$b $,x0.$ Also provide insights about how you would find an initial basic feasible solution for the models in order to start the Simplex method.

Consider the following linear programs:

$]=[7$

and

$ma{x}_x,2x_1,-7x_2,+6x_3,+5x_4$

$s.t.2x_1-3x_2,-5x_3,-4x_{4}20$

$,7x_1+2x_2,+6x_3,-2x_4=35$

$,4x_1+5x_2-3x_3,-2x_{4}15$

$,0x_{1}10,0x_{2}5,x_{3}2,x_{4}0.$