Lucia left a tip equal to 18% of the cost of her lunch. If she left $1.53 as her tip, what was the cost of her lunch, in dollars?

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it will cost dollar $540

the living room is 3 which means if we divide 325/3 then we get $108

therefore if 1part of the living room cost $108 and 3 costed $325

then total 5part of the room will cost 5*108 which gives $540