Point S makes the two connected angles the same. They both have right angles.
And one side of each is congruent.
This means you know 2 angles are the same and one side is the same.
You would use ASA (Angle, Side, Angle)
I think it would be C because the equation is y=7x. y=7x is also equal to x=1/7y. If y=45.50, then you would have to divide y by 7, which would equal 6.5.