Last week, Vivian spent a total of $20.00. She spent $9.95 for tickets to the school fair, $5.95 for food, and the rest for 2 rings
that were on sale at the school fair. If each ring had the same
cost, how much did each ring cost?
5th grade math

Really need on these. i have no idea what to do

After applying the composition r0.90 ry to rs what are the coordinates of r' and s'? a.r'(–3, 1),  s'(–3, 5)b.r'(–1, 3),  s'(–5, 3)c.r'(1, 3),  s'(5, 3)d.r'(5, 3),  s'(1, 3)

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.