0.25*23*0.04=1/4*23*0.04=23*0.01=0.23
10.2*4.5 =10.2*(9/2)=5.1*9=45.9
19.4*7.7+19.4*2.3=19.4*(7.7+2.3)=19.4*10=194
1.25*（7.4*9)=1.25*(8-0.6)*9=90-6.75