1/45+1/60+1/90=?

1/45+1/60+1/90=? (1/45+1/60-1/90)x=1 x/45+x/90-x/60=1 解方程 60(x+1)=90(x-1) 60(x+1)=90(x-1) 90,75,60,45,30,15,1哪里错误 x/45=1+(x+30)/60 X/45=(X+30)/60-1 x/60=(x-1)/45 (x-15)/45=(x/60)+1 45X=60（X-1） sin(45+&)sin(45-&)=1/6,90>& 60-1/5x+90=x (1/90+1/30)30+1/90*9+(1/90+1/60)X=1 X=?解方程, (2/45-1/90+1/36)*180 80%×45-60%÷1/45简算 （x-2)/30+(x-3)/45+x/90=1 已知tan(a+45)=-1/2,(90