Çözüldü Coprime Integers (Grade 8)

If 18 and A5 are two-digit coprimes, how many A5 numbers can be written?

A) 3
B) 4
C) 5
D) 6

A5 = {25, 35, 55, 65, 85, 95} ⇒ s(A5) = 6.
Note that 15, 75, and 18 are all divisible by 3.

https://drive.google.com/file/d/1bIJwF6RLQxJT7cNBixz07tZtk4qL9Pwh/view (The Last Question)
Answer Key: 1-D 2-C 3-B 4-C 5-B 6-B 7-B 8-D 9-D 10-C 11-B 12-A 13-C 14-A 15-A 16-D 17-C 18-B 19-B 20-D