По какой(-им) формуле(-ам) можно рассчитать длину световой волны?

It's
twenty to one
a quarter past eleven
twenty-five to nine
twenty past twelve
a quarter past eight
a quarter to nine
twenty-five past eight
half past eight
five to nine
eight o'clock
a quarter to eleven
five past eight

It's twelve forty.

It's eleven fifteen

It's eight thirty-five

It's twelve twenty

It's eight fifteen

It's eight forty-five

It's eight twenty-five

It's eight thirty

It's eight fifty-five

It's eight

It's ten forty-five

It's eight five

(Меня учили такому)