Using what you know about similar figure, solve for x

Since the scale factor is 3:1 you can multiply the length of the side of the triangle to the right by 3 to make the ratio 3:3

the equation would be:
2x+5 = 45

subtract 5 from both sides
2x = 40

divide both sides by 2

x = 20

hope this helps

One unique triangle, because those angles add up to 180, and that's how many degrees there are in one triangle.