Please do either 40 or 39

y = 1.8

Step-by-step explanation:

Question 39).

Let the operation which defines the relation between a and b is O.

Relation between a and b has been given as,

a O b =

Following the same operation, relation between 3 and y will be,

3 O y =

Since 3 O y = 4,

3 + y = 12 - 4y

3 + y + 4y = 12 - 4y + 4y

3 + 5y = 12

3 + 5y - 3 = 12 - 3

5y = 9

y = 1.8

Therefore, y = 1.8 will be the answer.