We know that there are 26 letters in the alphabet, and 10 different digit possibilities (0-9). We also know that the plates each have 3 letters and 2 digits. and they can be repeated. To solve this, we multiply 26 X 26 X 26 X 10 X 10 to get the total amount of possibilities 1,757,600. Hope this helps.
We presume the temperature is decreasing at midnight, so reaches a low at 6 a.m.. The amplitude of the variation is (87-63)/2 = 12 degrees. We want the period to be 24 hours, so the argument of the sine function will be 2π(t/24) = πt/12. Then we can write
