This is worth a lot of points and i’m

Is that a math question or a novel?

Inside.  Let d be the depth in km and t be the temperature in C at that depth.  We have an initial temperature of 15 C and an increase of 25 degrees C per km.  Our model is thus

t = 15 + 25d

or in slope intercept form

t = 25d + 15

At d=10 we expect a temperature of 265 C.

At d=40 we expect a temperature of 1015 C

Our range is 265 C to 1015 C, span of 750 C

Outside.  Same story, different slope.  d is now the altitude in km, Here we have a decrease of 6.5 C per km, so that's a negative slope.  Our model is

t = 15 - 6.5d

t = -6.5d + 15

At d=8 we get t= 15-6.5(8) = -37 C

At d=20 we get t=15-6.5(20) = -115 C

Range -115 C to -37 C, span of 78 C

c.

step-by-step explanation:

because first you have to add the 4x, 9x, and the 7x together and you get 20x and then you add the last numbers up and you get 5and then you put the subtraction sign in there and that's how you get the answer.