Bessey method for estimation of alkaline phostphatase takes benefit of substrate p-nitrophenyl phosphate forming colored product p-nitrophenoxide. (403 nm) To 2.40 ml of substrate containing buffer is mixed to 0.10 mL of serum. After five minutes, absorbance at 403 nm has changed by 0.550. Molar absorbtivity (e) of product is 18.8x10^3 L/mol cm. Determine activity of the enzyme in U/L?