If "a" varies directly as "b" and inversely as "c". If a=16 when b=12 and c=6, find "a" when b=28 and c=4. *

When b = 28 and c = 4, then a = 56

Step-by-step explanation:

We need to write the equation first

This is an example of a combined variation

if a varies directly as b and inversely as c;

then a = bk/c

where k is the constant of proportionality

We find k first;

16 = (12 * k)/6

k = (6 * 16)/12 = 8

We now want to find a

a = kb/c

a = (8 * 28)/4 = 7 * 8 = 56

goog may be able to you find that answer