21+4=25(чел)
25-6=19(чел)-было в бассейне
Ответ: 19 человек
<span><span><span><span>
а
</span><span>
10
</span><span>
100
</span><span>
1000
</span><span>
10000
</span><span>
100000
</span></span><span><span>
а*10
</span><span>
100
</span><span>
1000
</span><span>
10000
</span><span>
100000
</span><span>
1000000
</span></span><span><span>
а:10
</span><span><span> 1</span></span><span>
10
</span><span>
100
</span><span>
1000
</span><span>
10000
</span></span><span><span>
а+10
</span><span>
20
</span><span>
110
</span><span>
1010
</span><span>
10010
</span><span>
100010
</span></span><span><span>
а-10
</span><span>
0
</span><span>
90
</span><span>
990
</span><span>
9990
</span><span>
99990
</span></span></span></span>
(9*35)+(13*30)=315+390=705 рублей стоимость покупки