Answer:
The substance decays by 7.5% every year
Step-by-step explanation:
490.0...
4.9 x 10^2
(squared)
4.9 x 10 x 10
the easiest way to do this is to move the decimal 2 places to the right, as
10 x 10 = 100
4.9 x 100 = 490.0...
r≈4.75
26mph
18 miles at 36mph will take 30 minutes and 26 × 7 is 3 h 30 min
