Scientists are monitoring a whale's weight by observing its weight change once a week, over a 4 week period. how much has the whale's weight changed over the entire 4 weeks?

Option D. -3.9 will be the answer.

Step-by-step explanation:

Change in weight of the whale in first week = (-2.1) pounds

Change in weight of the whale in second week = (+0.3) pounds

Change in weight of the whale in 3rd week = (-1.7) pounds

Change in weight of the whale in 4th week = -0.4 pounds

Total change in weight over the period of 4 weeks = - 2.1 + 0.3 - 1.7 - 0.4

= -3.9 pounds

Therefore, Option D. -3.9 will be the answer.

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18

mx+89b(-98)nb

step-by-step explanation: