Directly Proportional vs. Inversely Proportional

anhtimmy
Mon, 29 Dec 2008 18:58:16 +0000

Want to know a trick?

(A/B)=(C/X)

Direct: use the “zig zag method”
X: (B x C)/ A
start with X, draw a line to the variable across it, draw a line to the letter above X, and finally across to the last.
The first two variables are multiplied and divided by the last.

Inverse: use “circle method”
X= (C x A)/ B

start from X, draw a line up, across the top, and back down the other side. The first two variables are multiplied and divided by the last.

draw it out, it’ll make sense. after you get this down, it’ll take you like 3 seconds to solve the question.