The sum of 3 consecutive odd integers is -21. Find the "middle" number.

A.-9
B.-3
C.-7
D.-5

Question

The sum of 3 consecutive odd integers is -21.  Find the "middle" number.
 





A.-9
B.-3
C.-7
D.-5

zepdrix · Answer

Here is a way you can represent this.

Let $\large x$ be some odd number, the first odd number.

The number after $\large x$ will be $\large \color{red}{x+1}$.
But this is not the number we want. We want the next ODD number.

The next odd number can be represented by $\large x+2$.
The odd number after that by $\large x+4$.

The `sum` of these odd numbers will be $\large -21$.

$\large x+(x+2)+(x+4)=-21$

Mmm maybe we should have set that up differently, oh well.
Based on the way I set this up, the `middle number` will be $\large x+2$.
So you don't want to solve for $\large x$. You want to solve for $\large x+2$.