Answer:
x = 2, y = -1
Step-by-step explanation:
To solve a pair of equations using substitution, first solve one of the equations for one of the variables. Then substitute the result for that variable in the other equation.
12x+15y=9,−12x−18y=−6
Choose one of the equations and solve it for x by isolating x on the left hand side of the equal sign.
12x+15y=9
Subtract 15y from both sides of the equation.
12x=−15y+9
Divide both sides by 12.
x= 1/12 (−15y+9)
Multiply 1/12 times −15y+9.
x = -5/4y+3/4
Substitute -5y+3/4 for x in te other equation, -12x - 18y = -6
-12 ( -5/4y+3/4) -18y = -6
Multiply −12 times -5y +3/4
15y−9−18y=−6
Add 15y to −18y.
−3y−9=−6
Add 9 to both sides of the equation.
−3y=3
Divide both sides by −3.
y=−1
Substitute −1 for y in x= -5/4y+3/4. Because the resulting equation contains only one variable, you can solve for x directly.
x= -5/4(-1)+3/4
Multiply -5/4 times -1.
x = 5+3/4
Add 3/4 to 5/4 by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.
x=2
The system is solved.
