Help please!! Spanish homework

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?

If the pants costs $233 how would you respond to the question ¿cuánto cuestan los pantalones?

Marcia tiene un bolígrafo y una tarjeta. a. está leyendo. c. está escribiendo. b. está jugando. d. está comiendo.