=(22/7)*(21/22)*(22/7-22/3)*(-7/22)
=(1/3)*[22*(1/7-1/3)]*(-7/22)
=(1/3)*(1/7-1/3)*(-7)
=(7/3)*(1/3-1/7)
=(7/3)*(1/3)-(7/3)*(1/7)
=7/9-1/3
=4/9