Answer:
answer d 242 square feet
Step-by-step explanation:
To find all the different possible combinations, you multiply all the possibilities for each position.
1st - she as 20 different possible buttons
2nd - she would have 19 possible buttons
3rd-she would have 18 possible buttons
20 x 19 x 18=6840 possible ways to choose these buttons.
Answer:
Step-by-step explanation:
=7 (1+11+111+1111......n)
=7/9 (9+99+999+9999....n)
=7/9 ((10-1)+(10^2-1)+(10^3-1)+....n)
=7/9 ((10+10^2+10^3...n)-(1+1+1+1.....n))
=7/9 ((10 (10^n-1)/(10-1))-n)
