Why is the value of a-1 always less than the value of a.

The - before the 1 represents it is less, so the -1 will always be less than a, since the - is before the one, and so that means the 1 is less than a.

-1 means to subtract 1, therefor whatever number you pick for a you subtract 1 therefore a will always be more

The answer is 10. and if you go by pemdas you would 1. multiplication 2. division 3. addition 4. subtraction