Question

solve by the substitution method
15x-10y=-5
15y=4+5x

Answer 1

(1) 15x-10y=-5
(2) 15y=4+5x

From (1) we have:

15x = -5 +10y
x = (-5+10y)/15 (1.1)

Substitute into (2):

15y=4+5[ (-5+10y)/15 ]
15y = 4 + (-5+10y)/3
15y = (12-5 + 10y)/3
15y = (7 + 10y)/3
45y = 7 + 10y
35y = 7
y = 1/5 ans.


Plug into (1.1):

x = [ -5+10(1/5) ]/15
x = ( - 5 + 2 )/15
x = -1/5 ans.