if a distibution has a mean of 50 and a standard devation of 25, how many standard deviation is 0 from the mean

Trent wants to buy 2 packs of trading cards for 3 dollars each. the trading card packs that trent normally buys tend to come in packs of 6, 10, 12, or 15 cards. after selecting 2 packs, trent found that the first pack of cards cost 25 cents per card, and the second pack cost 30 cents per card. trent uses this information to write the equations below in order to compare c, the number of cards in each pack.

:24% of students in a class are girls. if there are less than 30 students in this class, how many students are there? how many girls are there?

Fast! find the length of cu. the triangles are similar. show your work.