Grandfather distributed a bag of candies to Donald, Henry, and John, who got $70 \%$, $\mathbf{25 \%}$, and $5 \%$ respectively. Later Donald gave John 20 candies, and after that Henry and John shared their candies equally. By then Donald had three times as many candies as Henry. The next day Grandfather gave $x$ candies to each of the three persons, and Donald ended up having twice as many candies as Henry. Find $x$.
(1 mark)
Grandfather distributed a bag of candies to Donald, Henry, and John, who got $70 \%$, $25 \%$, and $5 \%$ respectively. Later Donald gave John 20 candies, and after that Henry and John shared their candies equally. By then Donald had three times as many candies as Henry. The next day Grandfather gave $x$ candies to each of the three persons, and Donald ended up having twice as many candies as Henry. Find $x$.
(1 mark)
3. 40
3. Suppose Donald, Henry, and John started with $14n$, $5n$, and $n$ candies respectively. After Donald gave John 20 candies and Henry shared candies with John, they had $14n-20$, $3n+10$, and $3n+10$ candies respectively. Hence we have $14n-20=3(3n+10)$, or $n=10$. In the end, Donald had $14n-20+x=120+x$ candies while Henry had $3n+10+x=40+x$ candies. Hence we have $120+x=2(40+x)$, giving $x=40$.