Simphiwe, a student, bought 50 memory sticks at A40 each for cash. All the memory sticks were marked 10 sell at R80 each. The sticks were sold for cash within 10 days, as follows 40 were sold at R8O each, 6 at R75 each and 4 at R70 each. The gross profit percentage on sales (calculated to the nearest 2 decimal places) is; 

a. 49,11%. 

b. 48.25% 

c. 96.5%

 d. 100%