18*7分之3+0.6*13分之8-7分之2*18-1又13分之5/1又13分之7
=18*3/7+0.6*8/13-2/7*18-(1+5/13)/(1+7/13)
=18*(3/7-2/7)+0.6*8/13-(18/13)/(20/13)
=18/7+3/5*8/13-9/10
=18/7+24/65-9/10
=2+4/7+48/130-117/130
=2+4/7-69/130
=2又37/910
18*(3/7-2/7)+3/5*8/13-13/18*20/13
=18*1/7+3/5*8/13-9/10