Jenny is making tie-dyed shirts for her class with her school colors, blue and yellow. She used a total of 8 ounces of fabric paint. The amount of blue paint is 3 times the amount of yellow paint.

Let's call the amount of yellow paint "y".

According to the problem, the amount of blue paint is 3 times the amount of yellow paint, so the amount of blue paint is 3y.

Together, the amount of blue and yellow paint equals the total amount of paint Jenny used:

3y + y = 8

Simplifying the equation:

4y = 8

y = 2

So Jenny used 2 ounces of yellow paint and 3 times that amount (6 ounces) of blue paint.

To solve this problem, we can create a system of equations.

Let's assume that the amount of yellow paint Jenny used is Y ounces.
So the amount of blue paint she used is 3Y ounces.

Since the total amount of paint used is 8 ounces, we can write the equation:

Y + 3Y = 8

Combining like terms:
4Y = 8

Dividing both sides of the equation by 4:
Y = 2

Now we know that Jenny used 2 ounces of yellow paint.
The amount of blue paint she used is 3 times that, so:

3 * 2 = 6

Thus, Jenny used 6 ounces of blue paint.
Therefore, she used a total of 2 ounces of yellow paint and 6 ounces of blue paint.