6,7y+13+3,1y=86,5
2,8+K+3,7=12,5
(5,6-y)+3,8=4,4

6.7у+13+3.1у=86.56.7у+3.1у=86.5-139.8у=73.5у=73.5:9.8у=7.52.8+к+3.7=12.5к=12.5-2.8-3.7к=6(5.6-у)+3.8=4.45.6-у=4.4-3.85.6-у=0.6у=5.6-0.6у=5

6.7y+3.1y=86.5-139.8y=73.5y=7.5k=12.5-2.8-3.7k=65.6-y+3.8=4.4-y=4.4-5.6-3.8-y=-5y=5