Algebra
posted by Andrea .
solve the linear system using substitution
4x  y=5
4x + 4y= 4
Also by using elimination.

substitution: since you have y = 4x5,
4x + 4(4x5) = 4
20x = 16
x = 4/5
y = 9/5
using elimination, subtract one equation from the other to get
5y = 9
y = 9/5
now solve for x to get x=4/5