You have two US coins that total $0.55 One of them is not a nickel. What are the two coins?

Two coins are "1 half dollar" and "1 nickel".

Step-by-step explanation:

It is given that we have two US coins that total $0.55.

We know that

1 penny = 1 cent = $0.01

1 nickel = 5 cents = $0.05

1 dime = 10 cents = $0.10

1 quarter = 25 cents = $0.25

half dollar = 50 cents = $0.50

1 dollar = 100 cents = $1

The given amount can be divide into two parts.

$0.55 = $0.50 + $0.05

$0.55 = 1 half dollar + 1 nickel

Therefore, the two coins are "1 half dollar" and "1 nickel".