Answer:
3x + 21 or 21 + 3x
Step-by-step explanation:
Remark
This is an example of the distributive property. Of all the fundamental rules used in solving equations, this is likely the most important, at least at beginning levels.
Solution
What this is saying is two things.
1. you must multiply both terms on either side of the + sign by the factor outside the brackets.
2. You must not destroy a plus (or minus) sign unless the two terms inside the brackets are exactly the same.
3(7 + x) The terms are not the same, so your answer must have a plus sign
Left side of the plus: 3*7
Right side of the plus: 3 * x
The answer then is 21 + 3x
It is more commonly written as 3x + 21
