Help my answer this question

ANSWERS:
(a) The cost of estimating the two pollution units are as follows:
    UNITS
    X
    Y
    Z
    1ST UNIT
    650
    55
    90
    2ND UNIT
    800
    70
    125
    TOTAL
    1450
    125
    215
Total = 1795
(b) If one permit to X is sold by Y and Z each, then Z and Y both have to reduce their pollution by 3 units and this reduction has a cost as reflected below:
Y = 55+70+110= 235
Z = 90+125+180 = 395
(i) Price is 390
The firm Y has to receive 390 and on the other hand pay 235 making a gain by netting the same. Therefore, Y is said to be willing.
The firm Y has to receive 390 and on the other hand pay 395 making a gain by netting the same. Therefore, Z is said to be unwilling.
(ii) If price is 55 or 70:
Both firms are in a position where they have to pay more than what they will...