Answer:
+7
Step-by-step explanation:
if you go from 28 to 21 you see there is a difference of 7 and sense the number is a smaller number now we know the dolphin went up more towards the surface there for there is a change of positive 7
28-21=7
1 + 1 = 2
1 and 1 = 2 1 and 1 =2 1+1=2 1+1=2
500 and 5,000
The value of the first 5 is five hundred (500)
The value of the second is five thousand (5,000)
15.92
50 ÷ 3.14 = 15.92