решаем системы сложения
1) {30х+15у=34.2|•1 {30х+15у=34.2
{5х+5у=7.9|•3. {15х+15у=23.7
(30х+15у)-(15х+15у)=34.2-23.7
15х=10.5
х=0.7
5*0.7+5у=7.9
5у=4.4
у=0.88
2){25х+20у=23.4|•1
{5х+5у=5.3|•4
25х+20у-20х-20у=23.4-21.2
5х=2.2
х=0.44
5*0.44+5у=5.3
5у=3.1
у=0.62
1) (х;у) = (0.7; 0.88 )
