Answers

2014-10-25T23:18:42+08:00
To have the lines parallel they must have the same slope.
getting the slope of the second equation you'll have:
9x + 8y = 15
having it the slope-intercept form, y=mx+b where m is the slope you'll have:
8y = 15 - 9x 
y = -9x/8 + 15/8
y = (-9/8)x + 15/8
slope, m=-9/8
from the first equation 
3x + 6ky = 7
6ky = -3x + 7 
y = -3x/6k + 7/6k
the slope is (-3x)/6k
equating the slope of the two equations you'll have:
 \frac{-9}{8} =  \frac{3}{6k}
cross multiply
-9(6k) = 3(8)
-54k = 24
k = -24/54
k = -4/9
0