$16.80 / 4 gallons = $4.20 per gallon
A composite number is one that can be made by multiply two numbers to each other. Since 49=7*7, 49 is a composite number.
Check:
You can check a multiplication chart, but you will see that 49 is the only one that can be multiplied by 2 numbers
The answer is the last one y=2.60z+180
The correct answer for the given question above would be the last option. The proper way to write a single digit whole number if it is in a sentence should be SPELLED OUT and not written in numerals or roman numerals. For example, I have SIX apples; and not I have 6 apples.