Answer:
440
The attached file is how I would have done it.
She wants to plant 200 bulbs in total, 3/4ths of which are tulips. So tulips will equate to 150 bulbs, while irises will equate to 50 bulbs.
This equation in numbers:
(-8x)^6 • (4x)^2
(262144•x^6) • (16x^2)
4,194,304x^8