Mario has 20 yards to mow this week. by wednesday, he had mowed 50% of the yards. how many yards had he mowed by wednesday? a.2 b.5 c.10 c.15

For this case we can make the following rule of three:
 20 yards ---> 100%
 x > 50%
 Clearing x we have:
 x = (50/100) * (20)
 x = 10 yards
 Therefore, by Wednesday he mowed 10 yards.
 
 he had mowed by Wednesday:
 C.10