Make y the subject of the following

a) 2b=1/1+y

2b = 1/(1+y)

Multiplying both sides by (1+y):

2b (1+y) = 1

Expanding the left side:

2by + 2b = 1

Subtracting 2b from both sides:

2by = 1 - 2b

Dividing both sides by 2b:

y = (1 - 2b)/2b