2△3= （2+3）/3 2/3△2/5= （2/3+2/5 ）/2/5 a△b=(a+b)/b 计算9/10△3/5

9/10△3/5
=(9/10+3/5)/(3/5)
=(3/2)/(3/5)
=5/2
x△3/4=2
即 (x+3/4)/(3/4) =2
x+3/4=3/2
x=3/2-3/4
x=3/4