Find each sum:

56 + (– 56)
(– 240) + 370
(– 5.7) – (– 4.2)

56 + (- 56) = 0

(- 240) + 370 = 130

(- 5.7) - (- 4.2) = - 1.5

Step-by-step explanation:

56 + (- 56)

56 - 56

0

(- 240) + 370

- 240 + 370

370 - 240

130

(- 5.7) - (- 4.2)

- 5.7 + 4.2

4.2 - 5.7

- 1.5

0, 130, -1.5

Step-by-step explanation:

Lets go over a few things that will help answer the questions:

A + and - make a - sign

A - and a - make a + sign

Ok, now lets sum our first expression:

56+(-56)

Remembering above that a + and - make a - sign:

56-(56)

=

0

Next:

(-240)+370

This is just a postive adding to a negative. So its:

-240+370=130

Finally we have:

(-5.7)-(-4.2)

This may look a bit confusing, so lets clean it up a bit:

The parethese around the -5.7 dont matter, and can be removed:

-5.7-(-4.2)

And remembering that a - and - make a +:

-5.7+4.2

Now adding the postive to the negative value:

-1.5

It is still a negative because the postive value being added to to -5.7 was smaller, so it still was negative, just a smaller negative number.

Hope this helps!

l.jnl.j/n.m,lm,

step-by-step explanation:

answer: 204

step-by-step explanation:

we are told that the revenue is

x⋅(4080−10x)=−10x^2+4080x

this is a quadratic function, so to maximize it we should find the x-value of its vertex. recall that the x-value of the vertex of the parabola ax^2+bx+c is given by the formula −b/2a.

so in this case, we have a=−10 and b=4080, so the x-value of the vertex is

−b/2a= −(4080)/2(−10)=204