Two lines, r and m, are represented by the following equations:

line r: 2x + 2y = 18
line m: x + y = 9

which statement is true about the solution to the set of equations? (4 points)

select one:
a. it is (18, 9).
b. it is (9, 18).
c. there are infinitely many solutions.
d. there is no solution