Can you deduct interest (primary house) from a home equity loan to buy a rental?

[John Davey]

Id appreciate any help, as ex. if i take out say 100k home equity loan and use 50k each as down payments/cloing costs my understanding is i cant deduct the interest?

However, if i would take 100k home equity on a rental A (ex. 100k) and use 50k each (same as above) for 2 rentals (B & C). I can deduct the interest, but it gets added it B and C vs A?