Please help me with my algebra.

The answer is infinitely many solutions.

Step-by-step explanation: We need to cancel the equations. If we multiply  x + y = 10 by -3 we could cancel the x, y, and the 30 too. x+y = 10 times -3. -3 times x is -3x. -3 times y is -3y. -3 times 10 is -30. If we try to cancel        -3x - 3y = -30  and 3x + 3y = 30 We can easily cancel all of the numbers. We get 0 = 0. In system of equations when we get 0=0 it means there is infinitely many solutions.

explanation:

previous steps have made pa≅ pb ≅ st ≅ su. setting the compass width to ab allows you to make tu the same length. then δstu ≅ δpab by the sss congruence postulate, and ∠p ≅ ∠s by the reason cpctc.