Explanation:
x = capacity of Marshfield
y = capacity of Browden
x + y = 210,355
x = y + 4,465
so, using the second equation in the first
(y + 4,465) + y = 210,355
2y + 4,465 = 210,355
2y = 205,890
y = 102,945 (Browden)
x = y + 4,465 = 102,945 + 4,465 = 107,410 (Marshfield)