How many different codes can a combination lock have if there are 4 numbers on the lock and each number can be from 0-9?

There are 10,000 possible combinations that the digits 0-9 can be arranged into to form a four-digit code. Suprisingly, people have an intense lack of imagination when it comes to choosing codes.

the entire expression should be subtracted from 30. to subtract the quantity, distribute the negative sign, which changes the signs on the terms. so, the –2 changes to positive and gets added to 30 instead of subtracted from it.

hope this ! ^w^