If two quantities x and y vary directly, then
As x and y varies directly that is x=ky where ,k is a constant, then k= x/y.So the correct answer is x/y
If two quantities x and y vary inversely then
As x and y varies inversely then, x=k/y,where k is any constant , so k=x X y. So the answer is x X y
If 8:12::6:a, the value of a is
8:12::6:a
→8/12=6/a
→8a=6X12
→a=6X12/8
→a=72/8
→a=9
So the answer is 9
If16×9=12×m, the value of m is
16 X 9=12 X m
16 X 9/12 = m
144/12= m
12=m .So the answer is 12
If the cost of 18 pens is Rs. 234, a dozen pen will cost
Cost of 18 pens= Rs 234
So Cost of 1 pen= 234/18=13
So a dozen pens( 12 pens ) will cost=
12 X13= Rs 156