34.8×0.25=4*0.25*8.7=8.7
7.43x6.5-74.3x0.55=7.43*(6.5-0.55*10)=7.43
83.4÷2.3+31.6÷2.3=(83.4+31.6)/2.3=115/2.3=50
49×11+49×36+49x54-49=49*(11+36+54-1)=49*100=4900
9999+6666x21+3333x55=3333*(3+2*21+55)=3333*100=333300