Solving System by substitution

What is the solution to this system?
y= 4x + 3
2x - 3y = 21

• (4,-9)
• (-3,-9)
• (3,5)
• (0,1)

What is the solution to this system?
y = 2x + 1
y = 4x - 1

• (1,3)
• (-1,6)
• (-5,7)
• (3,1)

What is the solution to this system?
x - y = 6
y= 2x - 5

• (3,3)
• (-4,3)
• (-1,-7)
• (1,-6)

What is the solution to this system?
6x + y = -1
y = -3x - 4

• (3, 1)
• (1, 6)
• (-3, 1)
• (1, -7)