Question 30887
i am assuming you mean: 4x+5y=20 and y=(4/5)x - 6


From y=(4/5)x - 6, multiply every term by 5:
5y = 4x - 30


Now sub this into the first equation giving 
4x+5y=20
4x+4x-30 = 20
8x-30 = 20
8x = 50
x = 50/8
x = 25/4


--> 5y = 4x - 30
5y = 4(25/4) - 30
5y = 25 - 30
5y = -5
y = -5/5
y = -1


Answer: (25/4, -1)


jon.