Hey there!!
What is a composite figure?
A composite figure is something which has two or more known shapes which are fixed or merged together.
As per the question, we have two shapes. which are the prisms.
The total volume would be the sum of the volumes of the two figures.
1st prism volume: (5)(7)(8)cm³
2nd prism volume: (10)(7)(4)cm³
... 280cm³ and 280cm³
Their sum is equal to the total volume.
... 280 + 280
... 560cm³ is the total volume of the composite figure.
Hope my answer helps!