From Yerevan and by bus

Use selected ablative, instrumental, and companionship expressions.

Origin: ablative

Երևանից = from Yerevan; դպրոցից = from school; տնից = from home. The selected ablatives express origin; տուն changes its stem.

Ես Երևանից եմ։

I am from Yerevan.

Means: instrumental

ավտոբուս bus → ավտոբուսով by bus; մատիտ pencil → մատիտով with a pencil. Learn these whole forms for transport and a writing tool.

Ես մատիտով եմ գրում։

I write with a pencil.

A person accompanying you

ընկեր = friend; ընկերոջ հետ = with a friend. հետ follows a genitive noun here. Do not replace companionship with the instrumental as though every English with were the same.