27-b<10, при b=18, 19, 20, 21, 22, 23, 24, 25, 26, 27.<br>27-18<10, да<br>27-19<10, да<br>27-20<10, да и так далее<br>
27-b>10, при b=0, 1, 2, 3, ...16.
27-0>10, да
27-1>10, да
27-2>10, да и так далее ....27-16>10, да.
27-b=10
b=27-10
b=17
27-17=10
10=10