Question

Solve the system of equations x+y=4 and 3x+7y=32 by combining the equations

Answer 1

Answer:

x = -1

y = 5

Step-by-step explanation:

x+y=4

3x+7y=32

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.

x+y=4,3x+7y=32

Choose one of the equations and solve it for x by isolating x on the left hand side of the equal sign.

x+y=4

Subtract y from both sides of the equation.

x=−y+4

Substitute −y+4 for x in the other equation, 3x+7y=32.

3(−y+4)+7y=32

Multiply 3 times −y+4.

−3y+12+7y=32

Add −3y to 7y.

4y+12=32

Subtract 12 from both sides of the equation.

4y=20

Divide both sides by 4.

y=5

Substitute 5 for y in x=−y+4. Because the resulting equation contains only one variable, you can solve for x directly.

x=−5+4

Add 4 to −5.

x=−1