2x^2+7x-5+(-8x^2-3x+5)=-6x^2+4x.
Answer:
630,630 different arrangements are possible for the given laptops.
Step-by-step explanation:
Total number of laptops = n = 15
Number of identical Dell laptops = 6
Number of identical Chromebooks = 4
Number of identical Mackbooks = 5
We have to find in how many ways can the laptops be arranged. Number of arrangement of objects is calculated using Permutations as the order of objects matter during the arrangement. The formula to calculate the number of possible arrangements when there are similar objects is given as:

Here n is the total number of objects and a,b, and c represent the number of identical objects. Using the given values we get:

This means 630,630 different arrangements are possible for the given laptops.
Answer:
12 inches × 12 inches × 12 inches
Step-by-step explanation:
Cube volume is 

![s=\sqrt[3]{1728}](https://tex.z-dn.net/?f=s%3D%5Csqrt%5B3%5D%7B1728%7D)

There's only information to answer question C.
We can only know that 32 marbles were chosen. (yellow and black)
Why?
To answer the first two questions (a and b), we need to know the total number of marbles, so, we can only answer the last question (c).
We know that 7/10 of the 20 yellow marbles were chosen.
So, calculating we have:

Also, we know that 18 black marbles were chosen, so, the total of marbles chosen is equal to 32 (yellow marbles and black marbles)

Have a nice day!