Would you mind telling how to say these kinds of things. Thanks

Q1. If the resolution of the screen is 1440x900, how to say to others?
Q2. $20.5 is twenty point five or $20.5 are twenty point five?
Q3. Beside twenty point five, do we have another way to say $20.5?
Q4. $20.5 is expensive or $20.5 are expensive?
Q5. 4:15, 4:30 and 4:45, how to say?


These question are confused me a long time ago.
Thanks for your attention.:-)

Q1. If the resolution of the screen is 1440x900, how to say to others? … the resolution is fourteen-forty by nine hundred
Q2. $20.5 is twenty point five or $20.5 are twenty point five? … it depends what you mean: $20.05 = twenty dollars and five cents … $20.50 = twenty dollars and fifty cents or twenty dollars fifty, but "twenty point five" = 20.5 (no dollar sign).
Q3. Beside twenty point five, do we have another way to say $20.5? … see Q2
Q4. $20.5 is expensive or $20.5 are expensive? … $20.50 is expensive.
Q5. 4:15, 4:30 and 4:45, how to say? … four-fifteen, four-thirty and four-forty-five (the use of hyphens may vary for different people)… or, a quarter past four, half past four, a quarter to five (these terms also vary with different regions).

not a teacher