Two-way lookup with INDEX and MATCH return closest match

Try this

Formula:

=INDEX($C$4:$D$8,IFERROR(MATCH(25,$B$4:$B$8,0),1+MATCH(25,$B$4:$B$8,1)),MATCH(G4,$C$3:$D$3,0))

where the values 1/2'' and 1'' are written with a single quote twice (code 039 not double quote code 112)
See the file to clarification