You are receiving two types of return on your XYZ shares: income (dividend) and capital growth.
In our example, the dividend is paid on 10,000 shares at 80 cents per share, which is $8,000. In addition our XYZ shares value has decreased from $10 to $8.50.
So your total return can be calculated as follows:
Dividend received (10,000 x 0.80) $8,000
Less capital loss ((10-8.5) x 10,000) ($15,000)
Total return ($7,000)
The total return is negative $7,000 on your $100,000.
To express this as a percentage it is $7,000 divided by $100,000. The return for XYZ shares is a -7% (-0.07) loss for that year.