Mary’s number is eleven more than Jerry’s. The sum of their numbers is 89. What are their numbers?

Jerry has a number of 39, and Mary has a number of 50.

Step-by-step explanation:

Let's say mary's number is x, and jerry's is y.

x-y=11 and y+x=89.  This means if we subtract 11 from 89 we get jerry's number times 2, which is 78. 78 divided by 2 is 39.    

Jerry has a number of 39    

and Mary has a number of 50.

because linear equations are a lot simpler than quadratics equations, and linear equations formula is a lot easier to memorize. that's why i think they're harder.