She bought the bike by 3,000 six years ago, we are assuming the value of her mountain bike depreciated 20% each year
1 year
3,000*20% = 600
2year
3,000-600 = 2,400*20% = 480
3year
2,400-480 = 1920*20% = 384
4 year
1920-384= 1,536*20% = 307.2
5 year
1,536-307.2= 1,228.8*20% = 245.76
6year
1,228.8 - 245.76 = 1,043.04*20% = 208.608
1,043.04 - 208.608 =834.432
Rounded to the nearest dollar
= 834