The following system of equations has a solution (x,y). What is the value of y?
21y=4
x−21y=2
Note that the first equation only has one solution for y.
21y=4
y=8
If we wanted to find the coordinate of intersection or use more familiar methods, we can use substitution. Note that 21y exists in both equations, which we can substitute directly.
21y=4
x−21y=2
x−4=2
x=6
Substituting back into the second equation,
6−21y=2
−21y=−4
y=8