"Over" or "under" are used for physical relationships.
Likewise, "above" and "below" are used to indicate positioning.
"Fewer" is used to indicate amounts of things that are counted individually.
"More" and "less" are used to indicate amounts of things that are counted in bulk, including money (unless you're referring to individual coins or bills.)
When referring to ages, use "younger" and "older."
Examples:
"The cow jumped over the moon."
"The city is 4,500 miles above sea level."
"Albert had fewer grapes than Janet."
"Less than 30 percent of Americans vote regularly."
no subject
Likewise, "above" and "below" are used to indicate positioning.
"Fewer" is used to indicate amounts of things that are counted individually.
"More" and "less" are used to indicate amounts of things that are counted in bulk, including money (unless you're referring to individual coins or bills.)
When referring to ages, use "younger" and "older."
Examples:
"The cow jumped over the moon."
"The city is 4,500 miles above sea level."
"Albert had fewer grapes than Janet."
"Less than 30 percent of Americans vote regularly."
"Stacy is four years younger than Willa."