Please tell me what question b and c is ASAP

Is a currency whose value is tied to another currency, meaning that the exchange is fixed

Describe in detail how you would construct a 95% confidence interval for a set of 30 data points whose mean is 20 and population standard deviation is 3. be sure to show that you know the formula and how to plug into it. also, clearly state the margin of error.

Simplify 15(x - 4)(x -1)-3(x + 4)(x - 1) with steps