For three weeks me park received less than a pound

Two customers went to a post office. first customer paid $12 for 14 and 5 envelopes the second paid 24.80 for 10 postcards and 15 envelopes. what is cost of each envelope?

Select the margin of error that corresponds to the sample mean that corresponds to each population: a population mean of 360, a standard deviation of 4, and a margin of error of 2.5%

Which equation shows y= 3 4 x− 5 2 in standard form? a 4x−3y=10 b 3x−4y=10 c 3x−4y=−10 d 4x−3y=−10