Row Range From Within A Data Range

I am trying to determine a range of rows which a number falls in between to restrict a secondary match criteria based on some keywords

I have two columns acting as a data range

Col A Col B
8 15
8 15
8 15
16 21
16 21
16 21
22 55
22 55
22 55

Then I have a value which I am trying to determine the min and max rows that the number fits in that range, where the min row is from ColA and the max row is from ColB.

i.e. the number 12 should give me the first row of column A and the last row of Column B that is the value nearest 12 i.e. row 3 with the value of 15

and the number 42 therefore would give me row 7 from column A and row 9 from column B

I have tried using;

INDEX(ROW(INDIRECT(RANGE)),MATCH(TRUE,INDIRECT(RANGE)>=INDIRECT(VALUE),0)

AND...............