Worked example

Operation: Find ?
a: 2
b: 3
c: 8
d: ?

→ d = 12

Method and scope

Simplification uses nonnegative integer a and positive b. For a:b=c:d enter exactly one ?. Denominators must be nonzero. Allocation accepts nonnegative weights and total, with a positive weight sum.

ad = bc; x₁ = T × a/(a+b); x₂ = T × b/(a+b)

Precision and limits

≈ marks an approximation. Display rounding does not change the internal calculation.