For perpendicular
lines:
"Their slopes' product is -1"
As these lines should be parallel, so their slopes would be the same.
Slope of line n:
8/14 = 4/7
Slope of the other line:
k/7
Equating them:
4/7 * k/7 = -1
4k / 49 = -1
4k = -49
k = - 49/4 = -12.25
This means
k= - 12.25Sorry for confusion