solve by subsituting
5x+4y=7
x-3y=9
put x= 3y+9 into the first equation for x, then solve for y.
I get 2 for y... does that sound right
To solve the given system of equations by substitution, we'll solve one of the equations for one variable and substitute it into the other equation.
Let's solve the second equation for x:
x - 3y = 9
To isolate x, add 3y to both sides:
x = 9 + 3y
Now, substitute this expression for x in the first equation:
5x + 4y = 7
Replace x with 9 + 3y:
5(9 + 3y) + 4y = 7
Distribute the 5 to the terms inside the parentheses:
45 + 15y + 4y = 7
Combine like terms:
19y + 45 = 7
Subtract 45 from both sides:
19y = 7 - 45
19y = -38
Divide both sides by 19:
y = -38/19
y = -2
Now, substitute the found value of y back into the second equation to find x:
x - 3(-2) = 9
x + 6 = 9
Subtract 6 from both sides:
x = 9 - 6
x = 3
The solution to the system of equations is:
x = 3, y = -2