Pls help tell me how to do it

Ateacher brought a pack of 17 batteries . each calculator uses 3 batteries . how many calculator can the teacher fill with batteries

Extremely mega ultra important question! plss answer as fast as you can you will get 84 points! the area of this right triangle is half the area of which of these rectangles?

Gabrielle's age is three times mikhail's age. the sum of their ages is 40 . what is mikhail's age? __ years old