the odometer of a car reads 68420 km when the clock shows the time 9 am if at 9 30 am the odometer reading has changed to 68540 calculate the speed of the car in km/min during this time

4 km/min

Explanation:

Applying

S = (d₂-d₁)/(t₂-t₁) Equation 1

Where S = speed of the car, d₁ = Intial reading of the odometer, d₂ = Final reading of the odometer, t₁ = initial time, t₂ = final time.

From the question,

Given: d₁ = 68420 km, d₂ = 68540 km, t₁ = 9:00 am, t₂ = 9:30 am

Substitute these values into equation 1

S = (68540-68420)/(9:30-9:00)

S = 120/30

S = 4 km/min.

answer: what are you talking about?

explanation:

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.