Answer:
315 red flowers
420 white flowers
315 yellow flowers
Explanation:
1050 flowers
3/10 of them are red=> 3/10 *1050=3*105=315 red flowers
2/5, (or 4/10), are white =>4/10 * 1050=4*105=420 white flowers
=> 1050-(315+420)=1050-735=315 yellow flowers