Solve the system of equations using the substitution method.

4x + 5y = 7

y = 3x + 9

x = - 2

y = 3

Step-by-step explanation:

Since y = 3x + 9, substitute this value in the first eq.

4x + 5 (3x+9) = 7 = ==> 4x + 15x + 45 = 7 = ==> 19x = 7-45 = => 19x = - 38 = ==>

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

Replace this value in the second eq.

y = 3 (-2) + 9 = ==> y = - 6 + 9 = ==> y = 3