Question

Before beginning voice lessons, Elizabeth already knew how to sing $ 15 $ pieces, and she expects to learn $ 2 $ new pieces during each week of lessons. How many weeks of lessons will Elizabeth need before she will be able to sing a total of $ 47 $ pieces?

Answer 1

Hint: For solving this particular problem we just have to take the difference of the total number of pieces she knows to the number of pieces she already knows , and then simply divide the result by two, this will give us the number of weeks she needs to learn.

Complete step-by-step answer:
We will find how many pieces she actually learns from her lessons ,
This is given as ,
Total number of pieces she knows – the number of pieces she already knew ,
Therefore, we will get ,
 $ 47 $ pieces - $ 15 $ pieces
This will equal $ 32 $ pieces .
Now , it is given in the question that she expects to learn $ 2 $ new pieces during each week of lessons.
Therefore, she need $ \dfrac{{32}}{2} $ weeks ,
That is $ 16 $ weeks .
She will take $ 16 $ weeks to learn the total of $ 47 $ pieces.
So, the correct answer is “16”.

Note: The solution of the addition or subtraction between two numbers will have the sign of the greater number. If there's subtraction between a positive and a negative number then there's addition.