istoas:sto

Each puzzle reads ___ is to ___ as ___ is to ___. Place the four tiles so both comparisons share the same relationship. The colon means is to.

Tap a tile to drop it in the next open spot, tap a placed tile to take it back, or drag tiles to rearrange them. Press Check when all four are placed. Swapping the two comparisons, or reversing both, still counts.

The theme is a nudge: the words may look unrelated until you see the link.