Can somebody tell me how to solve theses types of problems?

If there is 20 dogs in the shelter and 5 dogs get homes, and then 43 more dogs come. how many dogs are there in the shelter?

Anull hypothesis states that the difference between 8 hours of sleep and 3 hours of sleep has no effect on the number of pictures a student will remember during a picture memory interface test (pmit). examining the mit database, an extremely small t-value of 0.1611 is found. this t-value is much smaller than the smallest t-value on the chart for p-value reference. from this information we can: select one: a. accept the null hypothesis because the p-value obtained shows that the difference between the two groups being tested is not statistically significant b. accept the null hypothesis because the p-value obtained was statistically significant c. reject the null hypothesis because of the p-value obtained d. reject the null hypothesis because the data obtained is statistically significant

The continuous random variable x is uniformly distributed over the interval [–1,3]. find -e(x) -var(x) -e(x²) -p(x < 1.4) a total of 40 observations of x are made.