To solve for y in each given equation, we first need to isolate y on one side of the equation.

Equation 1:
5 1/2 - y = 0.15

To isolate y, we first need to convert the mixed number 5 1/2 to an improper fraction.
5 1/2 = 11/2

Now we can rewrite the equation:
11/2 - y = 0.15

To isolate y, we subtract 0.15 from both sides:
11/2 - 0.15 = y
11/2 - 1/6 = y
(11*6 - 1)/12 = y
(66 - 1)/12 = y
65/12 = y

So, y = 65/12 or y = 5.4167

Equation 2:
4 7/12 - y = 25

To isolate y, we first need to convert the mixed number 4 7/12 to an improper fraction.
4 7/12 = 55/12

Now we can rewrite the equation:
55/12 - y = 25

To isolate y, we subtract 25 from both sides:
55/12 - 25 = y
55/12 - 300/12 = y
(55 - 300)/12 = y
-245/12 = y

So, y = -245/12 or y = -20.4167

Therefore, the solutions for the equations are:
y = 65/12 or y ≈ 5.4167
y = -245/12 or y ≈ -20.4167