A typist uses a sheet measuring 20cm by 30cm lengthwise.If a margin of 2 cm is left on each side and a 3 cm margin on top and bottom, then percent of the page used for typing is

Area of the sheet =  $20\times 30cm2$  

Area used for typing =  $20-4\times 30-6cm2$   

required % = $\frac{384}{600}\times 100$=64%