Step 1: We make the assumption that 500 is 100% since it is our output value.
Step 2: We next represent the value we seek with X.
Step 3: From step 1, it follows that 100%= 500.
Step 4: In the same vein, X%= 210.
Step 5: This gives us a pair of simple equations:
100%= 500(1) X%=210(2)
Step 6: By simply dividing equation 1 by equation 2 and taking note of the fact that both the LHS (left hand side) of both equations have the same unit (%); we have
100%/X%= 500/210
Step 7: Taking the inverse (or reciprocal) of sides yields X%/100= 210/500 X= 42%
