Answer:
The decision rule is
Fail to reject the null hypothesis
The conclusion is
There is no sufficient evidence to show that the designer's claim of a better shoe is supported by the trial results.
Step-by-step explanation:
From the question we are told that
The population mean is 
The sample size is n = 25
The sample mean is 
The standard deviation is 
Let assume the level of significance of this test is 
The null hypothesis is 
The alternative hypothesis is 
Generally the degree of freedom is mathematically represented as

=> 
=> 
Generally the test statistics is mathematically represented as

=> 
=> 
Generally from the student t distribution table the probability of obtaining
to the right of the curve at a degree of freedom of
is

From the value obtained we see that
hence
The decision rule is
Fail to reject the null hypothesis
The conclusion is
There is no sufficient evidence to show that the designer's claim of a better shoe is supported by the trial results.
For this case we have:
Let x be the variable that belongs to the real numbers. Then, all reals less than 70 can be expressed as:

The tip of the inequality is directed to the real numbers, since they tell us that they are less than 70, for 70 the inequality remains open.
Answer:

A 10% tip on $23.47 is $2.35. To get this, you would multiply $23.47 by .1, which comes to 2.347, rounding to $2.35.
Answer is x-2. it goes down 2.