B=3c/d/ + a simplifying both sides of the equation then isolating the variable
9(n+3)=7n-3
1) distribute 9 into (n+3)
9n+27=7n-3
2) subtract 7n on both sides
2n+27=-3
3) subtract 27 on both sides
2n=-30
4) divide by 2
n=-15
Segments <em>AB</em> and <em>CD</em> are perpendicular.
