Answer:
[tex]\frac{5}{4}[/tex]
Step-by-step explanation:
We need to find the formula of line c
[tex]\left \{ {{a*2+b=1} \atop {6*a+b=6} \right.[/tex]
Subtract these two
-4*a=-5
a=[tex]\frac{5}{4}[/tex]
And lies c and d will be paraller if [tex]a_{c}= a_{d}[/tex]
so [tex]a_{d}[/tex]=[tex]\frac{5}{4}[/tex]
And that's the slope to line d
