Solve the system of equations and choose the correct ordered pair.

2x + 5y = 15
5x + 10y = 35

Multiply first equation by 2, 
4x + 10y = 30

Now, subtract first equation from second,
x = 5

Substitute the value in first equation, 
2(5) + 5y = 15
5y = 15 - 10
y = 5/5
y = 1

In short, Your Answer would be Option C) (5, 1)

Hope this helps!