The three refers to 3 ten thousands. or 3 x 10,000.
<u><em>Question 28:</em></u>
Subtract
on both sides
Divide
on both sides
<u><em>*(Answer)*=</em></u> 
<u><em>Question 30:</em></u>
Multiply
on both sides
Subtract
on both sides
<u><em>*(Answer)*=</em></u> 
Hope This Helps
BangtanBoyScouts