4/5÷[(1/2+2/5)×4/11]=4/5÷(9/10×4/11)=4/5×10/9×11/4=8/9×11/4=22/9
4/5÷[(1/2+2/5)×4/11] =4/5÷[(5/10+4/10)x4/11]=4/5÷(9/10x4/11)=4/5÷18/55=4/5x55/18=22/9