18 5/12 - 7/12*1 19/21-17/72*2/3
Решение примерчика18 5/12=221/121 19/21=40/217/12*40/21=280/252=10/9221/12-10/9=663/36-40/36=623/3617/72*2/3=34/216=17/108623/36-17/108=1869/108-17/108=1852/108=463/27=17 4/27