Each code will have one letter, followed by one digit, followed by three letters. The letters x ,y ,z, and will not be used. So, there are letters and digits that will be used. Assume that the letters can be repeated. How many employee ID codes can be generated?

the answer is 37

step-by-step explanation:

or

step-by-step explanation:

we need to solve for 'x' the following equation:  

we have that:

⇒

⇒ ⇒

factorizing, we get that:

  ⇒

then, the solutions are: or

nothing extraneous has been found!

for this case we must apply distributive property to the following expression:

the distributive property states that:

then, when applying the property we have to multiply the -2 for each term within the parenthesis: