The sand makes up a rectangular prism of dimensions 8' by 10' by 0.5'.
The volume of sand is then   V = L*W*H, or V = (10')(8')(0.5') = 40 cubic ft.
        
             
        
        
        
Step-by-step explanation:
45+90+x=180
135+x=180
x=180-135
x=45
 
        
             
        
        
        
The whole school would have 170 students that have a dog