What Mediterranean landmark is on Spain's southern border?

Last one for it’s in english but it’s kinda tricky! i’m not sure if it’s b, so can someone . i’ll make brainliest

Fill in the blank with the correct form of preterite or imperfect of the verb in parentheses. nosotros a la playa con ana ayer. (ir) answer for blank 1:

Achemist mixes 4 liters of one acid solution with 10 liters of a 40% solution, resulting in a 30% acid solution. what is the value of x, the acid concentration of the first solution