Okay, so if 1/3 of his yard is mowed in half an hour, "x" of his yard is mowed in an hour. 1/3 yard is to 1/2 hr as "x" yard is to 1 hr
Solve by cross multiplying: 1/2x = 1/3 *1 1/2x = 1/3 (divide both sides by 1/2) 2/3
Richard can mow 2/3 of his yard in one hour.
You can also figure this out by just realizing that 1/2 hr multiplied by 2 would give you 1 hr and then multiply 1/3 by 2 but it's good to get into the habit of solving things algebraically (or so I've been told).
