At blooming gardens nursery, they are currently running the following promotion: buy three trees of the same kind at the regular price and get the fourth at 80% off. jocelyn is needing some trees for her backyard and decided to buy four red oak trees using the promotion. the regular price for a red oak tree is $390.00. based on a tax rate of 8.25%, jocelyn ended up saving $ by using the promotion.

Regular price is
4 times 390=1560
tax=8.25%
1560 times 0.0825=128.7
add that
1560+128.7=1688.7 is price if didn't use promotion

if deal then
3 normall trees+1 that is 80% off
find the 4th tree
390 times 0.80=312 off
390-312=78
3 normal trees+78=3 times 390+78=1248
find the tax
0.0825 times 1248=102.96
add
1248+102.96=1350.96

compare prices

1688.7 no promotion
1350.96 with promotion
subtract
1688.7-1350.96=337.74

she saved $337.74