Final answer:
To solve the system of equations x + y = 1 and 5x - 4y = -7 by substitution, solve one equation for one variable and substitute it into the other equation. The solution is x = -1/3 and y = 4/3.
Step-by-step explanation:
To solve the system of equations x + y = 1 and 5x - 4y = -7 by substitution, we can solve one of the equations for one variable and substitute it into the other equation. Let's solve the first equation for x:
x = 1 - y
Now substitute this value of x into the second equation:
5(1 - y) - 4y = -7
5 - 5y - 4y = -7
-9y = -12
y = 4/3
Substitute this value of y back into x = 1 - y:
x = 1 - (4/3)
x = -1/3
So the solution to the system of equations is x = -1/3 and y = 4/3.