The ratio of money in Brian's wallet to Colin's wallet one day was 7:2. Brian spent £39 that day.

Brian now had £4 less than Colin.

How much did they initially have altogether?

What are the relative frequencies to the nearest hundredth of the columns of the two-way table?

Researchers were interested in whether relaxation training decreases the number of headaches a person experiences. they randomly assigned 20 participants to a control group or a relaxation training group and noted the change in number of headaches each group reported from the week before training to the week after training. which statistical analysis should be performed to answer the researchers' question?

True or false: the graph of y=f(bx) is a horizontal compression of the graph y=f(x) if b< 1