50+3/2+1*3/5+40+1/3+1*3/4+30+1/2+1*2/3
=50+3/2+3/5+40+1/3+3/4+30+1/2+2/3
=(50+40+30)+(3/2+1/2)+(1/3+2/3)+(3/4+3/5)
=120+1+1+3*(5+4)/(4*5)
=122+27/20
=123又7/20