Given y = k/x
x = 1/3, y = 162
x = ? when y = 3
when x = 1/3, y =162
162= k/0.333 or 3k/1
162 = 3k.
162/3 = k
k =54
y = 3
y = k/x i.e; 3 = 54/x
x = 54/3
x = 18
i hope its clear now...
for more problems of this type
http://www.glencoe.com/sec/math/algebra/algebra1/algebra1_03/study_guide/pdfs/alg1_pssg_G091.pdf
http://answers.yahoo.com/question/index?qid=20070405012616AAqPuup