3x + 4y = 15

(3x - y = 30

Enter the solution as an ordered pair.

The solution is

x = 9

y = - 3

Step-by-step explanation:

i will solve this equation simultaneously using the substitution method

so let

3x + 4y = 15 ... equation 1

3x - y = 30 ... equation 2

from equation 2

3x - y = 30 ... equation 2

y = 3x - 30 ... equation 3

substitute for the value of y in equation 1

3x + 4y = 15 ... equation 1

3x + 4 (3x - 30) = 15

3x + 12x - 120 = 15

15x - 120 = 15

15x = 15 + 120

15x = 135

divide both sides by 15 which is the coefficient of x

15x/15 = 135 / 15

x = 9

put the value of x in equation 3

y = 3x - 30 ... equation 3

y = 3 (9) - 30

y = 27 - 30

y = - 3