（1）5/18*1/4*90% =5/18×1/4×9/10=1/164/8/5-40% =4/8×1/5-2/5=1/10-4/10=-3/10(5/8+5/6)*4/25 =5/8×4/25+5/6×4/25=1/10+2/15=3/30+4/30=7/30（2）8/5x-120%=5.21.6x-1.2=5.21.6x=6.4x=43x+90%*4=9 3x+3.6=93x...