In sakura's garden for every 5 red flowers, there are 10 yellow flowers. there are a total of 75 yellow and red flowers in her garden. how many red flowers are in sakura'sgarden?

Let x = the number of yellow flowers
Let y = the number of red flowers.

There are a total of 75 flowers, therefore
x + y = 75              (1)
For every 5 red flowers, there are 10 yellow flowers, therefore
x = 2y                    (2)

Substitute (2) into (1).
2y + y = 75
3y = 75
y = 25
x = 2*y = 50

25 red flowers.