(0.91÷0.01）÷X= 1.3
9÷X=1.3
X=9÷1.3
X=6又12/13
1.6÷（X-0.45)=5又1/3
X-0.45=1.6÷5又1/3
X-0.45=0.3
X=0.3+0.45
X=0.751/5÷（X+0.68)=1/5X+0.68=1/5÷1/5X+0.68=1X=1-0.68X=0.32