Yes. Rational numbers are numbers that never end. 2.75 ends at the five. Therefore it is rational!
6 × 3 = 18
10 × 3 = 10
there for you would need 30 liters of cola for 18 guests
18:30
Cos(theta)=1/2
sin(theta)=(3^1/2)/2
tan(theta)=(3^1/2)
cot(theta)=1/(3^1/2)
csc(theta)=2/(3^1/2)