Can someone explain this I'm so confused

1. 15 : 5 + 1/2 · (-4/7)

2. - 7/10 + (-5/12) - (1/4)

A grade has 81 girls and 72 boys. the grade is split into groups that have the same ratio of girls to boys as the whole grade. how many girls are in a group that has 16 boys? 81:72, x:x, x:16

What statistical test and how many of them will need to be used to explore the difference in average cholesterol within each group before and after the treatment (i. e.

Write the equivalent fraction for 2/3

What is the average rate of change from x = - 1 to x=-3

The whole is eight one part is eight what is the other part?

When finding the surface area of a composite figure, why is it often necessary to subtract sides common to each individual shape? Complete the explanation.

To use the two sample t procedure to perform a significance test on the difference of two means, we assume: a) The populations' standard deviation are known. b) The samples from each population are independent. c) The sample sizes are large.

The USA won 15 Wimbledon championships. Sweden and Switzerland both won 7. Australia won 6, German won 4, and Spain won 2. Write the Ratio that compares the championships won by Australia to the total number of championships. Explain it's meaning.

How many solution does x^2=4x-5 have

Leonard used 2/7 of his paycheck