Apologies but I am having difficulty understanding how to convert a simple expression to a summation.

I have three parameters:

```
x = final rating
y = major criteria
z = minor criteria
```

The final rating is the sum of the major criteria (which is multipled by 2) and the minor criteria. So something like: $x = 2y + z$

But there can be multiple $y$ and $z$. For example, if I had 2 major criteria and 3 minor criteria, the expression would look like: $x = 2y{_1}+2y{_2}+z{_1}+z{_2}+z{_3}$

So would the summation look like this?

$$x = \sum_{n=0}{2y_n + z_n}$$

## Best Answer

the summation would look like: $$x=2\sum_{i=1}^m y_i+\sum_{j=1}^n z_j$$ where $m$ is the number of major criteria and $n$ is the number of minor criteria. the lower limit starts at 1.