How to solve for A and B given Y=A+B and Z =B+C

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Forgive me if this question is very simple or if my question is in wrong format.

I Have a set of random numbers let's say 7, 9, 1 And this could go on but only positive integers.

I have to add these numbers in a pyramid form...so that 7+9 =16, 9+1 =10 and so on..

Every time I move up a layer in the pyramid I have to remove the numbers in the layer below.

Once I am left with only two numbers to add at the top of the pyramid, I stop adding.

Now, I need to make my way down the pyramid again and figure the exact numbers I used to add up.

Can someone help me solve for this.

My idea is, If I am left with two numbers at the top of the pyramid I am left with 16 and 10... I know that $$ 1 6 =A + B \quad \text{and} \quad 10 = B + C. $$

I need to solve for A, B and C.

I am happy to clarify if nor well understood.

Thanks in advamce

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Looks like it is impossible. The system of these equations has multiple solutions. You can take $B=2$ => $A=14, C=8$ - that's one solution. Or you can take $B=3$ => $A=13, C=7$ -it's a different solution.

As a rule of thumb - number of (independent) equations should be equal to number of unknown variables - in this case there is a single solution. If number of equations is larger - there is no solutions. If it is smaller - there are multiple solutions. This is not a strict rule (the equations could be dependent) but usually it works.

Things are much more complicated if there is a requirement that all variables are integers, but simple counterexample works in this case: you can't solve the system of equations.