Just "plug n chug" as my teacher would say. In other words, replace the letters with the values.
Choice A is (7,19) which means x = 7 and y = 19. Let's replace the x and y value with these numbers in both equations. If we get a true equation, then we found the answer.
2x-y = -5 2*7-19 = -5 14-19 = -5 -5 = -5 ... true So that works. Let's try the other equation x+3y = 22 7+3*19 = 22 7+57 = 22 64 = 22 ... false So choice A is NOT the answer because of this. Let's try out choice B 2x-y = -5 2*4-9 = -5 -1 = -5 ... false so B doesn't work either. How about C? 2x-y = -5 2*8-21 = -5 -5 = -5 ... that works x+3y = 22 8+3*21 = 22 71 = 22 ... but this is false So D has to be the answer. Let's check to confirm or not 2x-y = -5 2*1-7 = -5 -5 = -5 ... true x+3y = 22 1+3*7 = 22 22 = 22 ... true BOTH equations are true at the same time so (1,7) is definitely the final answer
Congruent triangles have the exact same three sides and the exact same angles. They are identical. So if you look at your triangles carefully, they are congruent. :)
