What two devices in a computer should be considered "black boxes," and should never be opened due to risks involving charged capacitors?

Ihave 25$ on an itunes card and i need to buy spotify premium, i have no other payment method.

The total cost of textbooks for the term was collected from 36 students. create a histogram for this data. $140 $160 $160 $165 $180 $220 $235 $240 $250 $260 $280 $285 $285 $285 $290 $300 $300 $305 $310 $310 $315 $315 $320 $320 $330 $340 $345 $350 $355 $360 $360 $380 $395 $420 $460 $460

In which part of a professional email should you try to be brief, but highly descriptive?