given that A,B,C and D are whole numbers such that A*B=8, B*C=28, C*D=63 and B*D=36, find the values of A,B,C and D.

A*B=8, B*C=28, C*D=63 and B*D=36 
C*D=63 tells us that C and D are odd in fact one of them is likely 7. Assume C=7. 

B*C=28 means B=4, and so 
A*B=8 means A=2 
checking B*D ... 
4*9 = 36 

so... 
A=2, B=4, C=7, D=9 


:)