0.5 x 4 = 2 feet / 2 feet in 4 seconds
15 - 2 = 13
New depth: 13 feet
0.4 x 3 = 1.2 feet / 1.2 feet in 3 seconds
13 - 1.2 = 11.8
New depth: 11.8 feet
Answer:

Step-by-step explanation:
After every Half life , Half of the mass is left.
After 1st Half life = 100 g / 2 = 50 g
After 2nd Half life = 50 / 2 = 25 g
After 3rd Half life = 25 / 2 = 12.5 g
After 4th Half life = 12.5 / 2 = 6.25 g
![\rule[225]{225}{2}](https://tex.z-dn.net/?f=%5Crule%5B225%5D%7B225%7D%7B2%7D)
Hope this helped!
<h3>
~AH1807</h3>
Answer:
280
Step-by-step explanation:
1514-1234 = 280