[(0.9减去五分之一)÷4又八分之三+1.8]乘以3又七分之四=（7/10÷35/8+1.8）x25/4=(8/25+9/5)x25/4=8/25x25/4+9/5x25/4=2+45/4=13又1/4九分之八乘以[八分之七减去(十六分之七减去八分之一)] =8/9x(7/8-5/16)=8/9x9/16...