What is the answer for number 15 16 17

15.

6 pachages
each pcage has 30
6*30=180 total

17 left over
how many used
used=total-left over
used=180-17
used=163

16. xy is 2 digit number
multiplules of 10 (whole multipules) always end with 0 so y=0

and has 3 as one of its factors
factors of 3 is 3,6,9,12
30,60,90 is answer

17.
30 in 9 parks
30 times 9
30=10 times 3
3*10*9
group the 3 and 9
10*(3*9)
3*9=27
10*(27)
270

15. 163
16. 30,60,90
17. see above, 270