Necesito ayuda con número uno y dos por favor. Pls no links!

Fill the blank with a la, a los, a las, or al. los alumnos

Okay so i'm taking an online spanish course (penn foster), and in the study guide, you have to create a bunch of sentences with words you've learned so far. translating, reading, and those kinds of things are fairly easy, but when it comes to making my own sentences, my brain just kinda waltz's away. anyone got any tips?

Fill in the blank: la ruta del camino de santiago es de aproximadamente millas.