My understanding is that marijuana contains little THC. It has complex alkaloids which break down into THC when exposed to heat. ie burn.
The required temperature for conversion is more than 100 C, which means brewing a tea would not be efficient.
Fats and oils have higher boiling points than water and are sufficiently high enough to break down the marijuana alkaloids into THC, which is why cooking marijuana in brownies is efficient.
The alkaloids in dry marijauna are relatively stable and store well. THC is less unstable and doesn't preserve well especially when exposed to sunlight, oxygen, warm temperatures, excessive moisture...
Just add finely ground up marijauna to the brownie mix and cook well done. Expect results 30-60 minutes after eating. Do not drive or operate dangerous equipment while under the influence. Find a safe place with some friends. Don't make an ass of yourself. Be discreet.
Store uneaten brownies in a cool dry place away from children and animals. Sealed in plastic and frozen is best. Mark the container with a skull and crossbones, three big XXX's or some other scary symbols so your brownies are not accidently ingested by your mother...