17 less than the sum of a number and 8.
First of all we have the phrase less than which mathematically
translates as what? If you said subtraction you are doing
great!! Again, you need to be careful with this phrase - it is very
tempting to start off with 17 and put your subtraction sign after the 17
- however, think about it, if you want 17 less than something you are 17
below it, in order to be 17 below something you would have to subtract
the 17!!! So you would not have 17 minus but minus 17 as PART of
The other part of the expression involves the phrase 'the sum of',
which would be what mathematical operation? Addition would be the correct response to that.
And as always, when we have a phrase like 'a number' where we have a
unknown number, we replace that with a variable.
Let's see what we have: