Mathematics for IGCSE & O level - Proportion (Section 2 - No. 28)
If *A* varies directly as *B* and inversely as *C*, then which of the following is true?
*A* = kBC
*A* = kB/C
*A* = kC/B
BC = kA
Paliwanag
If A varies directly with B and inversely with C, then A = k(B/C)