Describe the relationship between a and b that will make the value of the expression 7×a/b equal to 7

We have the following equation:
 7 * (a / b) = 7
 There is only one possible way for this equation to be fulfilled.
 For this, necessarily:
 a = b
 Substituting we have:
 7 * (a / a) = 7
 7 * (1) = 7
 7 = 7
 
 The relationship between a and b is:
 a = b