<span>240:(y:15)-18=42</span>
<span>240:(у:15)=42+18</span>
240:(у:15)=60
у:15=240:60
у:15=4
у=4*15
у=60
Ответ:60
<span>240*15:y=42+18</span>
<span>3600:у=60</span>
<span>60у=3600</span>
у=3600:60