Question

Using addition elimination method please solve this:
6c - 9d = 103 and 5c - 9d = 103 please show work.

Answer 1

Sorry the first equation equals 111.

Answer 2

6c - 9d = 111
5c - 9d = 103

Subtract second from first to get c=8
Substitute c=8 in equation 1 to get 9d=48-111=-63 or d=-7
Substitute both c and d in second equation to check answer.

Answer 3

- ok so for using addition elimination method so for this you need firstly multiply the second equation by -1 and hence will get for second equation -5c+9d=-103
- so now adding these equations will get

6c-9d=111
-5c+9d= -103
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(6c+(-5c)+(-9d+9d)=111+(-103)
(6c-5c)+0=111-103
c+0=8
c=8

so than 6*8-9d=111 so 48-9d=111 so -9d= 111-48 so -9d=63 so d= 63/(-9)
so d= -63/9 = -7

than we get

c=8
d= -7