(1)24×43分之51+51×43分之19
=24*51/43+19*51/43
=51/43*(24+19)
=51/43*43
=51
(2)17分之22×12分之7-12分之5×17分之7
=7/17*22/12-5/12*7/17
=7/17*(22/12-5/12)
=7/17*17/12
=7/12