Solve using substitution. (C& D)

2C+3D=1

-3C+D=15

Equation 2

-3c+d=15

d=15+3c

Substitute into eq 1

2c+3 (15+3c) = 1

2c+45+9c=1

11c=-44

c=-44/11

c=-4

Sub into eq 1

2 (-4) + 3d=1

-8+3d=1

3d=9

d=9/3

d=3

Verify:

2 (-4) + 3 (3) = 1

-8+9=1

1=1 - - True.

2c + 3d = 1 ⇒ 2c + 3d = 1 ⇒ 2c + 3d = 1

-3c + d = 15 ⇒ 3 (-3c + d) = 15 ⇒ - 9c + 3d = 15

-7c = 16

-7c = 16

-7 - 7

c = - 2 2/7

2 (2 2/7) + 3d = 1

4 4/7 + 3d = 1

-4 4/7 - 4 4/7

3d = - 3 4/7

3d = - 3 4/7

3 3

d = - 1 4/21

(c, d) = (-2 2/7, - 1 4/21)