Answer: 50. 4g 
Step-by-step explanation:
First calculate number of moles of aluminium in 38.8g 
Moles = 38.8g/ 26.982mol/g
 = 1.44mol
By looking at the balance equation you can see that 4 moles of aluminium produce 2 moles of aluminium oxide. 
4 = 2
1.4 = x
Find the value of x 
x= (1.4×2)/4= 0.72 mol
0.72 moles of aluminium oxide are produced from 38.8g of aluminium 
Now find the mass of aluminium produced. 
Mass = moles × molar mass 
 = 0.72mol × 69.93 mol/g
 = 50.4g