У + 4 - у+1 = 6у
6у=5
у=1,2
5x-3y=8 -1=7 y+2x=5 (5-2x=3y)
1)11 1/63*9=11*9+1/63=99 9/63=9:9/63:9=99 1/7
2)12 1/35*5=12*5+1/35=60 5/35=5:5/35:5=601/7
3)99 1/7-60 1/7=99-60=39
{ a + b = 120
{ 1,1a + 0,8b = 111
{ a = 120 - b
{ 1,1*(120 - b) + 0,8b = 111
132 - 0,3b = 111
0,3b = 21
b = 70 a = 120 - 70 = 50
Ответ: {50; 70}