Currently, each student in our school system is assigned a 6-digit (each
digit is 0-9) student identification number.
As the school system plans for the future, they are considering using a 7th
character, that will be a letter (each letter can be A-Z).
Use the counting principle to determine how many unique student
identification codes can be created with these 7 characters (1 letter
followed by 6 digits).

26,000,000 codes

Step-by-step explanation:

To find how many unique codes can be created, we just need to check how many possibilities there are for each letter or digit in the code.

Each letter has 26 possible values, and each digit has 10 possible values, so as we have 1 letter and 6 digits, the total number of unique codes are:

26 * 10 * 10 * 10 * 10 * 10 * 10 = 26,000,000 codes.

step-by-step explanation:

ok so im not 100% sure but you would start by adding 5.1t and 1.9t beacuse they have the same variable. that is 7t.   then add -3.6 + 1.2 which is -2.4

so then keep that as -2.4 + 7t. i apologize if this is incorrect. best luck on your test < 3