X÷1又5分之1=6.4；
x÷(6/5)=6.4;
x=(6/5)×6.4;
x=7.68;
X-9分之4X=4.5÷2又7分之1
5x/9=4.5÷(15/7);
5x/9=2.1;
x=3.78;