15:0,5=30см
6*30=180см
7*30=210см
Р=30+180+210=420см
4х-3у=12 (*4)
<span>3х+4у=34 (*3) </span>
<span>
16х-12у=48 </span>
<span>9х+12у=102 </span>
<span>
25х=150 </span>
x=150 : 25
x=6
<span>
3*6+4у=34 </span>
<span>4у=16 </span>
y=16 : 4
y=4
<span>ответ: (6;4) </span>