Sweet
expression, い adjective
This is a single kanji with an い on the end, meaning you know it's probably an adjective. What's the adjective form of sweet? It's sweet.
あまい
The reading is the same as the one you learned with the kanji.
甘いケーキと美味しいワインを買って、うちに招待すれば、必ず友達を作れるよ。
My sure-fire way to make friends is to buy some sweet cake and good wine and invite them over.