In a:b::b:c: which is called the

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1 + 1 =
Solve this simple math problem and enter the result. E.g. for 1+3, enter 4.

In a:b::b:c: which is called the

Fires proportional of a,b and c.

Fourth proportional of a, b, and c.

Second proportional of a, b, and c.

Third proportional of a, b, and c.