The lifespan of a zebra is 15 years. The lifespan of a black bear is 3 years longer than the lifespan of a zebra

Question

I have to write an addition equation to find what the lifespan of a black bear is 

Answer 1

If B = the lifespan of a black bear, and Z = the lifespan of a zebra, then we could form the following equation:

 

B = Z + 3

 

Since Z = 15, we would have B = 15 + 3 = 18