In a science experiment the temperature of a substance is changed from 42 °f to -54 °f at an average rate of -12 degrees per hour. over how many hours does the change take place? the answer is 8 hours i need the work for it though.

3. solve the given inequality and graph the solution on a number line.

Add the two expressions 3.8b - 7 and 2.9b + 9 enter your answer in simplified form

Summary statistics given for independent simple random samples from two populations. use the pooled t-interval procedure to obtain specified confidence interval. x1=71.6, s1=3.9, n1=11, x2=67.9, s2=3.4, n2=9 determine a 99% confidence level.