The radius is 2 and area = r^2*pi so 4*pi gives you 12.56 so the exact answer would be 12.56 and the answer with pi would be 4 times 3.14!
Look at this video: https://www.khanacademy.org/math/cc-fifth-grade-math/cc-5th-fractions-topic/cc-5th-multiplying-fraction-whole-number-product
Inverse property of multiplication.
These are not similar. For them to be similar, they need to exist in proportion to each other for every single side. The ratio of the 12:9 sides is 4:3 when reduced. The ratio of the other 2 sides is 5:3. They all have to have the same ratio for them to be similar.
That system has D. no solutions