I've always said "$100 were taken" not "$100 was taken" because I thought $100 is plural. Could you explain why "was" not "were"? Any other helpful notes about the issue would be appreciated.
Nearly £20 was taken from my bank account
Because phrases that indicate the amount of sum, time, distance, weight, temperature, etc. are treated as singular:
10 million pounds is a lot of money.
= This sum is a lot of of money.
50 liters of petrol fills my car.
= This quantity fills my car.
Five kilometers is a long way to walk.
= This distance is a long way to walk.
Fifty degrees is a very high temperature.
= This temperature is a very high temperature.
And so on.
If a box had contained twenty one-dollar bills, then one might say "twenty dollars were taken from the box" [note that the above might possibly written as "20 dollars", but not as "$20"]. If the box had contained a single twenty-dollar bill, however, the verb should clearly be singular. Further, unless the taking consisted entirely of one-dollar bills, the only significance of the number "twenty" would as a description of a single value. The notation "$20" doesn't generally mean twenty individual dollars, but instead is shorthand for "a quantity of money with the same value as twenty individual dollars". Since any verb would bind to "quantity", rather than the dollars which would have the same value, the verb should be singular.
Nearly £20 was taken from my bank account
While 100 dollars is plural so you naturally say were. But twenty quid was taken. Wiki - The word Quid was also used in connection to multiple pounds
You could also say 20 clams were taken or 20 of my finest bills were taken. But it would be a score was taken. Similarly twenty bob, nicker, wedge or wonga would be was. But 20 smackeroos were taken.
100 $1 bills were taken from me
vs1 $100 bill was taken from me
desu
being the copula at the end. A good way to think about the copula is it being the equal sign.