4. (8 pts) Consider the following system of equations: x1+2x23x3+5x4+x5=45x12x2+6x4+x6=82x1+3x22x3+3x4+x7=3x1+x32x4+x8=0wherex1,x2,,x80 Let (x5,x6,x7,x8)=(4,8,3,0) be an initial basic feasible solution. Suppose that x1 becomes basic. Which of the given basic variables must become nonbasic to guarantee that all the variables remain nonnegative, and what is the value of x1 in the new solution? Repeat this procedure for x2,x3, and x4. Hint: Use the minimum ratio test