After three half-lives of an isotope, 1 billion (one-eighth) of the original isotope's atoms still remain in a certain amount of this element. how many atoms of the daughter product would you expect to be present?

The half-life is simply the amount of time it takes for half of the isotope to decay into something else. 

After 1 half-life, half of the original sample remains. After a second half-life, half of that part remains or 1/4 of the originalafter 3 half-lives, 1/8 remains and so on. 

In your example, ut started with 8 billion atoms. After one half-life, there was 4 billion. After a second half-life, there was 2 billion and after 3, one billion remain.

The horse latitudes-high-pressure zones about 30 degrees north and 30 degrees south of the equator.-warm air traveling away from the equator cools and sinks-weather tends to be clear and drythe doldrums-low-pressure near equator-air rises and spreads out toward the poles-rising moist air produces clouds and heavy rainthe westerlies-blow from the west-move from the horse latitudes toward the poles.-bring storms across much of the united statesthe tradewinds-blow from the east-move from the horse latitudes toward the equator  -strong, steady winds