I am painting a house! For monies!

I'm home from college for a couple more weeks now, and I've been asking around for jobs. This lady at my church has one for me: painting her house. The paint's covered with mildew, so she needs me to spray it with this chemical solution to dissolve the mildew first. Then I'm going to have to prime it. Then, paint it. The house is 1275 square feet, I believe. She reckons it'll take about three days all told--one day for each step. Here's my question: how much should she pay me for this? She has no idea herself, and I of course have never had to pay someone to paint my house as I have never owned a house. I'm figuring I'll ask about 80-85% of the professional rate. So, anyone know what the going rate is for a job like that?

Jam it back in, in the dark.

Aaaand a week later:

Thanks for all your advice. She ended up deciding to pay me by the hour. And as for the job, I thought painting an entire house in three days sounded a tad ambitious too... until I learned that all I was doing was painting the eaves on a brick house with wooden trim. And she paid me $8 an hour. Doesn't sound too awesome, until you factor in that she also, for some unfathomable reason, paid me for my lunchbreaks. W00t!

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