原式=[(49/90×7/20)+(1.65×20/20)×(49/90)-(1×49/90)]÷[2又14/15-4+2又14/15]
={(49/90)×[(7/20)+(33/20)-1]}÷[2×(2又14/15)-4]
=(49/90)÷(28/15)
=7/24