2.24×2.5+17.76÷0.4=2.24×2.5+17.76÷2/5=2.24×2.5+17.76×5/2=2.24×2.5+17.76×2.5=2.5×(2.24+17.76)=2.5×20=50
2.24x2.5+17.76/0.4=2.24x2.5+17.76x2.5=2.5(2.24+17.76)=2.5x20=50