甲数是a,乙数是甲数的3倍,乙数是 .
a+74=74+ a×c+c×b= ×( + )
把算式补充完整,使之能简算. ①2.5×1.36×0.4= ×( ×0.4)②7.5×0.48+0.48×2.5=(7.5+ )× .
18+(82+75)=(18+82)+75根据 .
7.2×9+2.8×9=(7.2+2.8)× = .
125×24=125× × 250×12=250× × .