We have to solve 24+0.79T=1.19T where T is the number of tiles, the left side is the total cost for the first store and the right side the cost for the second store.
Combine the T terms: 0.40T=24, so T=24/0.40=60 tiles.
CHECK
24+0.79T=24+47.40=71.40=1.19*60