7x - 3y = 20

y = 5 х - 4

x=

y=

x = - 1

y = - 9

Step-by-step explanation:

7x - 3y = 20

7x - 3 (5 х - 4) = 20

7x - 15x + 12 = 20

-8x = 20 - 12

x = 8/-8

x = - 1

7x - 3y = 20

7 (-1) - 3y = 20

-7 - 3y = 20

-3y = 20 + 7

-3y = 27

y = 27/-3

y = - 9