six less than 3 times the sum of a number n and seven
We put in a parentheses around "the sum of a number n and seven"
and a bracket around 3 times (the sum of a number and 7)":
six less than [3 times (the sum of a number n and seven)]
First we express what's in the parentheses:
"the sum of a number n and seven" is expressed as n+7.
So now we have:
six less than [3 times (n+7)]
Now we express what's in the bracket:
"3 times (n+7)" is expressed as 3(n+7)
So now we have:
six less than [3(n+7)]
To express six less than something we subtract 6 from it:
3(n+7)-6
That is the expression, not simplified.
Edwin
