Step-by-step explanation:
Let x = sculpture
Let y = painting
Let z = photograph
From the statements
The top three prices for works of art sold at auction in 2013 totaled $305.8 million.
and
The selling price of the painting was $51.9 million more than that of the photograph.


Together, the painting and the photograph sold for $25.2 million more than the sculpture.
Thus, we will have

We are to find the value of x, y, and z
We will follow the steps below
step 1:

Step 2:

Step 3: Simplify

Step 4

Step 5: Simplify

Step 6:

Step 7


Therefore,
The selling price of the sculpture was $140.3 million.
The selling price of the painting was $108.7 million.
The selling price of the photograph was $56.8 million.