Beng, Chandra and Danial have some stickers. Chandra and Danial have 7/10 of the stickers. Beng and Danial have 6/7 of the stickers. Beng and Chandra have a total of 620 stickers. How many more stickers did Danial collect than Beng?

Guest Feb 11, 2015

#7**+5 **

I'm just doing this one to see if I can solve it without "cheating" and looking at other's answers.....!!!

Let N be the total number of stamps....so we have

C + D = 49/70N (1)

B + D = 60/70N (2)

B + C = 620

Adding (1) and(2), we have

620 + 2D = (109/70)N → D = (109/140)N - 310

So

B + C + D = N

620 + (109/140)N - 310 = N

310 = (31/140)N → N = 1400

So D has (109/140)(1400) - 310 = 780

And B has

780 + = (6/7)(1400) → D = 1200 - 780 = 420

So D - B = 780 - 420 = 360 more

CPhill
Feb 11, 2015

#2**+5 **

Beng and Danial have 6/7 of the stickers ,so chandra have 1/7 of the total stickers

so Danial have 7/10-1/7=39/70 of the total stickers , so beng have 6/7-39/70=21/70=3/10

Beng and chandra have 1/7+3/10=31/70,so the Danial ,Beng and chandra have 620/31*70=1400

Danial collect more 1400*(39/70-3/10)=1400*（9/70）=180 stickers than Beng

Guest Feb 11, 2015

#3**0 **

I think we need an adjudicator on this one - I don't have time at present

Thank you :))

Melody
Feb 11, 2015

#4**+5 **

i made a mistook.

39/70-3/10=39/70-21/70=18/70

(18/70)*1400=360 ,so Danial collect more 360 than Beng.

i am so sorry guys.

Guest Feb 11, 2015

#5**+5 **

**Beng, Chandra and Danial have some stickers. Chandra and Danial have 7/10 of the stickers. Beng and Danial have 6/7 of the stickers. Beng and Chandra have a total of 620 stickers. How many more stickers did Danial collect than Beng**

$$\small{\text{

All Stickers $=x$

}}\\\\

\begin{array}{lcccc}

(1) & b+c+d=x & \quad c+d=x-b &\quad b+d=x-c &\quad b+c=x-d\\\\

\hline \\

(2) & c+d = \frac{7}{10}x &\frac{7}{10}x = x-b \\\\

(3) & b+d = \frac{6}{7}x & &\frac{6}{7}x = x-c \\\\

(4) & b+c = 620 & && 620 = x-d \\\\

\hline \\

& b+c+d=x & b=\frac{3}{10}x & c=\frac{1}{7}x & d=x-620\\\\

\end{array}\\

\begin{array}{rrcl}

& \frac{3}{10}x + \frac{1}{7}x + x-620 &=& x\\ \\

& x &=& 1400

\end{array}$$

$$\\b=\frac{3}{10}*1400 = 420\\\\

c=\frac{1}{7}*1400 = 200\\\\

d=1400-620 = 780\\\\

d-b=780-420 = 360$$

How many more stickers did Danial collect than Beng? 360

heureka
Feb 11, 2015

#7**+5 **

Best Answer

I'm just doing this one to see if I can solve it without "cheating" and looking at other's answers.....!!!

Let N be the total number of stamps....so we have

C + D = 49/70N (1)

B + D = 60/70N (2)

B + C = 620

Adding (1) and(2), we have

620 + 2D = (109/70)N → D = (109/140)N - 310

So

B + C + D = N

620 + (109/140)N - 310 = N

310 = (31/140)N → N = 1400

So D has (109/140)(1400) - 310 = 780

And B has

780 + = (6/7)(1400) → D = 1200 - 780 = 420

So D - B = 780 - 420 = 360 more

CPhill
Feb 11, 2015