tertre

Thanks so much, CPhill! 

I don't understand your question.

Wait, but I know 7^2-6^2=13, which is prime...

Oh, but I know that difference between the consecutive numbers=sum of the numbers.

Welcome, CPhill! 

is  this correct?

10b=7c, b=7/10c

So, 4x=7/10c, x=7/10/4=7/10*1/4=7/40c

9x=7/40*9=63/40c.

a=63/40c

Wait, so is it 63:40?

Thank you, CPhill! 

Hmm, let me try this one.

We know that a:b=9:4, and 10b=7c, so that means b:c=10:7

a:b=9:4

c:b=7:10   Find the LCM of 4 and 10, which is 20.

So, a:b=45:20

c:b=14:20

Thus, the answer is 45:14

We know that the 

 number of men : number of women : number of children = 13:5:7, and there are there are 4152 more men than women.

So, m=w+4152, or 13x=5x+4152

Solving for x, we get 8x=4152, x=519

Children=7x, so the answer is 519*7=\(\boxed{3633}\)

Yes, I think that's correct! Well done, Gavin! 

Hint: use y=mx+b

Latex: \(1 \cdot \frac {1}{2} + 2 \cdot \frac {1}{4} + 3 \cdot \frac {1}{8} + \dots + n \cdot \frac {1}{2^n} + \dotsb.\)