Derek dragon became a vegetarian two years ago. Derek likes to eat 3 baskets full of apples and 5 baskets full of berries for his birthday feast. But this year he can’t find many berries so he settles for 4 baskets of apples and only 1 basket of berries instead. Surprisingly, he feels equally satisfied. His mind drifts back to the old times when humans in metal suits used to clank into his cave. They made a nice crunchy breakfast treat!

How many baskets of berries will satisfy this dragon for his next birthday feast?