The rent you are receiving on your property is $100 per week for 52 weeks, which is $5,200 p.a.
There are expenses of $800 p.a., so your net rent income is $4,400.
In addition your property value has increased by $3,000.
So your total return is calculated as follows:
Rent received $5,200
Less: expenses ($800)
Add capital growth $3,000
Total return $7,400.
The total return is $7,400 on your $100,000.
To express this as a percentage it is $7,400 divided by $100,000. The return for the property is 7.4% (0.074).