P=2(a+b)=42
2(a+3/7)=42
(2a+3/7)=42
2a+3/7-42=0
2a+18=0
2a=18
a=9
2(9+b)=42
18+2b=42
2b=42-18
2b=24
b=12
(9+12)*2=42
1) 999*3/4 и 999:3/4
2997/4 и 999*4/3=333*4/1=1332
749,25 < 1332
999*3/4< 999:3/4.
<span><em><u>25.500кг</u></em>
</span><span><em><u>2т 5 ц</u></em>
</span><em><u>вот эти.......</u></em>