Question

Solve the system is equations and choose the correct answer from the list of options.

d+e=15

-d+e=-5

Label the ordered pairs as (d,e).

Answer 1

d+e=15
-d+e=-5 
The ds cancel out so
e=15
e=-5
Add both sides of equations together
2e=10
Divide by 2
e=5 

Substitute 5 for e in either equation:
d+5=15
Subtract 5
d=10

(10,5)