How can I divide a range of cells by another range of cells and then sum them up
You can do this with another area used for intermediate computation. I use another table on a separate Reference sheet.

Example:

|---------|---------|---------|-------------|
| 1       | 2       | ...     | SUM(C1:C10) |
|---------|---------|---------|-------------|
| 3       | 4       | ...     |             |
|---------|---------|---------|-------------|
| A1 / A2 | B1 / B2 | ...     |             |
|---------|---------|---------|-------------|


(The bottom row would be in the other table.)