Look for capturing opportunities for White and you see RxR, but Black’s rook has protection. So turn your attention to the piece that guards the rook—the bishop on f5. You can’t capture it, and it protects nothing else you can capture. You might consider chasing it away with g3-g4, but then Black simply plays RxR himself; after you recapture BxR, he moves his bishop to e6 and has lost nothing. The position comes apart promptly, however, once you notice that the f5 bishop is aligned with its king and thus is pinnable. Bg4 does the trick for White. A bishop pinning a bishop can be awkward, of course, but not when the pinned bishop is supposed to be protecting a more valuable piece. Suddenly it is paralyzed and does no defensive work. If Black plays BxB (his best move), White has RxR and wins the exchange. If Black instead plays RxR, White doesn't recapture BxR—yet. First he plays BxB+, using the priority of check to gain a move. Black has to move his king, and then White still has BxR waiting for him.