29又四分之一乘三分之四加39又五分之一乘四分之五加49又六分之一乘五分之六
=(30-3/4)x4/3+(40-4/5)x5/4+(50-5/6)x6/5
=30x4/3-3/4x4/3+40x5/4-4/5x5/4+50x6/5-5/6x6/5
=40-1+50-1+60-1
=147