Answer two questions about Systems A and B:
System A
{ x - 4y = 1
{5x + 6y = -5

System B
{x = 1 + 4y
{5x + 6y = -5

How can we get System B from System A?
A. Replace one equation with itself where a quantity is added to only one side
B. Replace one equation with itself where the same quantity is added to both sides
C. Swap only the right-hand sides of both equations
D. Swap the order of the equations