Answer :

so 1/5d=-3 so you multiply both sides by 5d/1 so you get
5d/1 times 1/5d=5d/1 times -3/1
so the above statement simplifies to 5d/5d=5d times -3 or
1=-15d
so you multiply both sides by -1
-1=15d
divide both sides by 15
-1/15=d