Solve the following system of equations by the substitution method. 10x + 10y = 1 x = y - 3 what is the value of y? -29/20 31/20 -3/2

31/20

Step-by-step explanation:

10x + 10y = 1 (1)

x = y - 3

substituting x = y - 3 in equation (1)

10(y - 3) + 10y = 1

10y - 30 + 10y = 1

20y - 30 = 1

20y = 1 + 30

20y = 31

divide 20 by bothside

20y/20 =31/20

y=31/20

multiply second equation by 2 and rewrite

4a + 6b = 10

4a - 8b = 24

subtract equations

0 + 14b = -14

14b = -14

b = -1

sub back into 4a + 6b = 10 to find the value of a

4a + 6 (-1) = 10

4a - 6 = 10

4a = 16

a = 4

therefore, 12a = 12×4