Solve the linear system of equations using the linear combination method

4x + 5y=7

y=3x+9

Enter your answers in the boxes.

x=

y=

x = - 2

y = 3

Step-by-step explanation:

Write the system the following way:

4x + 5y = 7

-3x + y = 9

we need to eliminate one unknown by multiplying one equation for a suitable number in such a way that when we add the equations one unknown is eliminated.

If we multiply the second eq. by - 5 the y is eliminated

4x + 5y = 7

15x - 5y = - 45

add the equations

19x = - 38 = ==> x = - 38/19 = ==> x = - 2

Now replace this value in any equation to get y. For example, in 1st one.

4 (-2) + 5y = 7 = ==> - 8 + 5y = 7 = ==> 5y = 7+8 = ==> 5y = 15 = ==> y = 15/5 = ==>

y=3