I know the answer. I don't know how to get to the answer to this problem:

The number of marbles Mari has is 2/3 the number Tanya has. Together they have 40 marbles. How many marbles does Tanya have? I know the answer is 24, but how?

The total number of marbles is 2+3 units, or 5 units.

5 units = 40.
Divide 5 from each side, and get 1 unit = 8.
Tanya has 3 units, so 3 units = 24 Ans.

http://www.jiskha.com/display.cgi?id=1407079093

To solve this problem and find out how many marbles Tanya has, you need to set up an equation based on the given information.

Let's assume that Tanya has x marbles. According to the problem, Mari has 2/3 of the number of marbles Tanya has. So, Mari has (2/3)x marbles.

The problem also tells us that together they have 40 marbles. So, we can write the equation:

x + (2/3)x = 40

To simplify this equation, we can convert the fraction into a decimal:

x + (2/3)x = 40
(3/3)x + (2/3)x = 40
(5/3)x = 40

Next, we can isolate x by multiplying both sides of the equation by the reciprocal of (5/3), which is (3/5):

(5/3)x * (3/5) = 40 * (3/5)
(15/15)x = 120/5
x = 24

So, Tanya has 24 marbles.