Hi there, there are 2 questions here that I cannot figure out. Will appreciate if anyone can enlighten me.

15)Devi went shopping with an equal number of $2 and $5 notes. She spent 20% of her $2 notes. She withdrew some $5 notes from the bank and had 30% more $5 notes than before. In the end, Devi has 15 more $5 notes than $2 notes.

a)How many $2 notes did Devi spend? (Ans:6)
b)How much money did Devi have at first?(Ans:$210)

16)Mrs Lim gave her two daughter, Liming and Lizhen, some money in the ratio of 8:9. Liming and Lizhen shared the cost of an electronic game in the ratio of 6:7. Liming used 3/4 of her money to pay for her share of the electronic game. Lizhen was left with $130 after paying for her share.

a) How much did Liming get from her mother? (Ans:$520)
b) What was the cost of the electronic game?(Ans:$845)

15)
$5 : $2
100%:100%
After she spends 20% of her $2 notes
and added 30% more $5 notes she now has
130% :80%

50% > 15u
20% > 20/50x15=6
She spent 6 $2 notes

50% > 15u
100% > 15x2 =30 $5
100% > 15x2 =30 $2
Total $150+$60=$210

Liming : Lizhen
8 : 9

6 : 7 shared the cost of the game

3/4 of Liming's money is 6u
Therefore Lizhen's share is 7u
Lizhen's remaining 2u is $130
1u is $65
a) Liming got $65x8=$520
b) The cost of the game is 13x$65=$845

Saraswathi wrote:
[quote]15)


50% > 15u
20% > 20/50x15=6
She spent 6 $2 notes

Hi, I do not quite understand how you arrived to these numbers that are highlighted in blue. Can you explain in details?

Devi went shopping with an equal number of $2 and $5 notes. She spent 20% of her $2 notes. She withdrew some $5 notes from the bank and had 30% more $5 notes than before. In the end, Devi has 15 more $5 notes than $2 notes.

a)How many $2 notes did Devi spend? (Ans:6)
b)How much money did Devi have at first?(Ans:$210)

Hi Ally, perhaps this solution will help with your understanding.



Note: I have chosen 10units at first because I wish to have whole numbers in my ratios. If I use a ratio of 1 : 1 then taking 20% of 1 will result in a decimal. I could use 5 as 20% of 5 is 1 thus 80% is 4, however, 30% of 5 produces a decimal. Thus the best option is 10units as 20% of 10 is 2 and 30% of 10 is 3.

Alternatively I could start with 100 : 100 and arrive at
80 : 130 and then simply to 8 : 13.