Question

Can you guys please help me with number 13 and with shown work

Answer 1

Explanation:

Let's solve for c.

6c−9d=111

Step 1: Add 9d to both sides.

6c−9d+9d=111+9d

6c=9d+111

Step 2: Divide both sides by 6.

6c

6

=

9d+111

6c=3/2 d+37/2

Answer:

c= 3/2 d+37/2

Second one

Let's solve for c.

5c−9d=103

Step 1: Add 9d to both sides.

5c−9d+9d=103+9d

5c=9d+103

Step 2: Divide both sides by 5.

5c

5

=

9d+103

5c =9/5 d+103/5

Answer 2

c=8, d = -7

Explanation:

6c - 9d = 111

5c - 9d = 103

Multiply the second equation by -1

-5c + 9d = -103

Add this to the first equation to eliminate d

6c - 9d = 111

-5c + 9d = -103

------------------------

c = 8

Now we need to find 9

6c - 9d = 111

Substitute in c=8

6(8) -9d = 111

48 - 9d = 111

Subtract 48 from each side

49-48 -9d = 111-48

-9d =63

Divide each side by -9

-9d/-9 = 63/-9

d = -7