Level 3
Carl had a total of 90 notes. The notes are $10 notes and $5 notes. After he spent 20% of the $10 notes and 60% of the $5 notes on a stereo system, he was left with 4 times as many $5 notes as $10 notes. How much did the stereo system cost?

Level 3
The ratio of the number of biscuits in Container H to the number of biscuits in Container J was 5 : 3. 20% of the biscuits in Container H and 0.6 of those in Container J were round. After transferring the biscuits between the 2 containers, the number of square biscuits in both containers are the same. Likewise, the number of round biscuits in both containers are the same. If a total of 162 of biscuits were moved, how many more biscuits were there in Container H than Container J at first?

Level 3
Mrs Yap had 40% more books than Mdm Zhang. Miss Lin had 20% fewer books than Mrs Yap. Mrs Yap and Mdm Zhang gave Miss Lin some books in the ratio of 1 : 4. As a result, Miss Lin had 50% more books than before. Given that Miss Lin had 423 more books than Mdm Zhang in the end, how many books did Mrs Yap give to Miss Lin?

Level 3
At an event held at the stadium, 80% of the audience were adults. The female audience was made up of 70% of the children and 30% of the adults. There were 64 more girls than boys.

1. How many people went to the stadium in total?
2. Some women left before the event ended, after which 20% of the remaining people at the stadium were women. How many women left the stadium before it ended?

Level 3
Oscar, Ethan and Fred had some balls. Ethan had 40% more balls than Oscar. Ethan had ³₅ of Fred's. After Oscar gave 18 balls to Ethan, he had ¹₂ of what Ethan had. How many more balls did Fred have than Ethan in the end?