Indicate which of the following is an all-integer linear program and which is a mixed-integer linear program. Write the LP Relaxation for the problem but do not attempt to solve.
a. Max 30x1 + 25x2
s.t.
3x1 + 1.5x2 ≤ 400
1.5x1 + 2x2 ≤ 250
1x1 + 1x2 ≤ 150
x1, x2 ≥ 0 and x2 integer

b. Min 3x1 + 4x2
s.t.
2 x1 + 4x2 ≥ 8
2 x1 + 6x2 ≥ 12
x1, x2 ≥ 0 and integer