At first, the ratio of dave's savings to sam's savings was 5: 4. after each of them donated $40 to charity, the ratio of dave's savings to sam's savings became 13: 10. what was dave's savings at first?

Which expression shows the result of applying the distributive property to -2(1/3x - 1/5) right answer pls.. 2/3x + 2/5 -2/3x - 2/5 2/3x - 2/5 -2/3x + 2/5

Which sum or difference identity would you use to verify that cos (180° - ∅) = -cos ∅? a. sin (α -β) = sin α cos β – cos α sin β b. cos (α -β) = cos α cos β – sin α sin β c. cos (α -β) = cos α cos β + sin α sin β d. sin (α + β) = sin α cos β + cos α sin β

Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.1. (round your answers to four decimal places.) (a) if the distribution is normal, what is the probability that the sample mean hardness for a random sample of 8 pins is at least 51?