Solve for both systems: 7y+5x=79 and 7y + 7x = 91

7y + 7x = 91

7y-7y + 7x = 91-7y

7x = 91-7y

7x /7= 91-7y/7

x=13-y

7y+5x=79

7y+5(13-y)=79

7y+5(13) (5)(-y)=79

7y+65-5y=79

2y+65=79

2y+65-65=79-65

2y=14

2y/2=14/2

y=7

x=13-y

x=13-7=6