(x-y)/4=4-(3x+y)/8
(x+3y)/2-(4x-y)/5=3

(x-y)/4=4-(3x+y)/8 
0.625x-0.125y-4=0 

y=5x-32

(x+3y)/2-(4x-y)/5=3
(x+3*(5x-32))/2-(4x-(5x-32))/5=3
(x+15*x-96)/2-(4x-(5x-32))/5-3=0
16x/2-96/2-(4x-(5x-32))/5-3=0
8x-48-(4x-(5x-32))/5-3=0
8x-48-(-x+32)/5-3=0
8x-48-(-x/5+6.4)-3=0
8x-48+x/5-6.4-3=0
8.2x-48-6.4-3=0
8.2x-54.4-3=0
8.2x-57.4=0

x=57.4/8.2

x=7
 
(x-y)/4=4-(3x+y)/8 
(7-y)/4=4-(3*7+y)/8  

7/4-y/4-4+(3*7+y)/8=0

-2.25-y/4+(3*7+y)/8=0

-2.25-y/4+21/8+y/8=0

-2.25-y/4+2.625+y/8=0

0.375-y/4+y/8=0

0.375-0.125y=0

y=0.375/0.125

y=3

Ответ: x=7; y=3.