Ok, let's find how much does 1 yard of ribbon cost. Let's divide!

Each yard costs $1.50, so let's multiply that by 10

Marci will pay $15 for 10 yards of the ribbon.
I have my work at the bottom but to explain you have to divide 30/12, and I got 2.5. That means 30 is 2.5 times bigger than 12. Because we have to find x, we have to divide 7/2.5, to find what is 2.5 times smaller than 7. That’s 2.8. So, x= 2.8
C. Similar - AA
There is no information given that shows differences between the two triangles so you can assume that they're similar. The two angles are next to each other with no side interrupting them, and no side length is given, therefore the answer is Similar - AA (angle - angle)