Use substitution to solve this linear system :

x+3y=7
5x-4y=-10

Question

Use  substitution to solve this linear system :

x+3y=7
5x-4y=-10

anonymous · Answer

(1)   x+3y=7
(2)   5x-4y= -10

from (1) we have:
        x = 7 - 3y    (1.1)

Plug (1.1) into (2) and we have:
        5(7-3y)-4y= -10
        35-15y-4y = -10
        35 - 19y = -10
             - 19y = -10 - 35
             - 19y = -45

                    y = (-45) / (-19) = 45/19

use the result to find x with (1.1)

         x = 7 - 3(45/19)
         x = 7 - 135/19

         x = (133-135) / 19 = -2 / 19



is that right?