1) 3.3a+a-4=4.3a-4
<span>2) 5a-0.7a-8=4.3a-8
</span><span>3) 5.3b-2b-3=3.3b-3
</span><span>4) 9.6b+7-0.4b=9.2b+7
</span><span>5) 2c-9+5.1c=7.1c-9
</span><span>6) -5c+13-6c=13-11c</span>
12ч24м+9ч18м=22ч.10м
12*60=720+24=744
9*60=540+18=558
744+558=1302
1302:60=21.70 или 22ч 10 мин