48:4*3=36 отрезали
48-36=12 осталось
--------------------------------
х+15=18+7
х=25-15
х=10
----------------------
24+х=10+21
х=31-24
х=7
-------------------
=(16/24+21/24-20/24)*(17/17-5/17)=17/24*12/17=1/2
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(3 3/42-2 10/42)*0,6=(2 45/42-2 10/42)*3/5=5/6*3/5=1/2