Answer:
3
[tex]d\in R,\hspace{5}d\neq 0[/tex]
Step-by-step explanation:
You can solve for any variable. From the first equation, let's solve for c :
[tex]\frac{c+1}{d} =5\\\\c+1=5d\\\\c=5d-1[/tex]
Now, replace the value of c into the other equation:
[tex]\frac{30d}{2c+2} \\\\\frac{30d}{2(5d-1)+2} \\[/tex]
Using distributive property
[tex]\frac{30d}{10d-2+2} =\frac{30d}{10d} =3[/tex]
However, keep in mind that this is true for:
[tex]d\in R,\hspace{5}d\neq 0[/tex]
