Respuesta :
Your answer should be costó (or if I'm wrong, cuestá should be your answer)
El almuerzo costó quince euros (This would work if you already have bought it)
or
El almuerzo cuestá quince euros (This would work if you still haven't bought it)
El almuerzo costó quince euros (This would work if you already have bought it)
or
El almuerzo cuestá quince euros (This would work if you still haven't bought it)
El amuerzo cuesta quince euros. (1)
El almuerzo costó quince euros. (2)
(1) está en en presente mientras que (2) está en pasado. En algunas frases como esta se puede poner presente y pasado.
English:
1) is in the present tense while (2) is in the past tense. In some sentences like this you can put present and past.