Given the Partial Project Network Below and the Fact That $\ge$

Essay

Given the partial project network below and the fact that F can be crashed three times if x_t = start
time of Activity i, and y_i = amount of crash time used for Activity i.
a. Which of the following is correct? x_F $\ge$ x_D + 10 - y_D or x_F $\ge$ x_E + 10 + y_E or y_D, y_E $\le$ 0 or x_F -x_D - x_E + 10 $\ge$ 3
b. Which of the following is correct? y_D $\le$ 3 or y_E $\le$ 3 or y_F = y_D + y_E or y_F $\le$ 3