Đáp án:
` (7+x)/(1+5y) = (5+3x)/(11) = (3+5x)/(3+y)`
Ta có
` (5+3x)/11 = (3+5x)/(3+y)`
` => 3+y = 11`
` => y= 11-3 = 8`
Thay ` y = 8` vào ` (7+x)/(1+5y) = (5+3x)/11`
` => (7+x)/(5*8+1) = (5+3x)/11`
` => (7+x)/41 = (5+3x)/11`
` => 41*(5+3x) = 11*(7+x)`
` => 205 + 123x = 77+ 11x`
` => 112x = -128`
` => x = -128/112 = -8/7`
Vậy ` x = -8/7 ; y = 8`