I will give you the brainliest if you get this correct If you solve this you get 100 points.
There are 10 red and blue marbles, among which r are red. How many are blue? Denote blue marbles as b.

r + b = 10

Step-by-step explanation:

r + b = 10

Since we don't know how many of either red or blue there is you just use the variables to make an equation.

Since there are 10 marbles in two different colors red and blue we can add red and blue to equal the total.

r + b = 10

Step-by-step explanation:

Let red be r and blue be b obviously, there is know way to solve this other than to guess because there can be many values for this

My guesses:

There is 1 blue marble: (Remeber the equation above) so 9+ 1 = 10 marbles

There is 2 blue marbles: 8 + 2 = 10

There is 3 blue marbles so 7 + 3 = 10

There is 4 blue marbles so 6 + 4 = 10

There is 5 blue marbles so 5 + 5 = 10

There is 6 blue marbles so 4 + 6 = 10

There is 7 blue marbles, I think you see the connection

6mm^3 or .6cm^3

      216

      /   \

  36     6

  /   \     /

6     6   6

factor trees are nice.