Answer:
8 weeks
Step-by-step explanation:
week 1=64
week2=32
week3=16
week4=8
week5=4
week6=2
week7=1
week8=.5=0
You would set it up: .5/100 = x/490 and then cross multiply .5 time 490 and 100 times x, and end up with: 245=100x. divide by 100, and get 2.45
45/100 is 4,500%
2/5 is 40%
18/40 is 45%
15/25 is 60%
