Plz help 15 points and brainliest if you are correct Prove the sum of two rational numbers is rational where a, b, c, and d are integers and b and d cannot be zero.

Steps Reasons
1. a over b plus c over d Given
2. Multiply to get a common denominator
3. ad plus cb all over bd Simplify
Fill in the missing step in the proof.

Group of answer choices

ac over bd

ad over b plus cb over d

a plus c all over b plus d

ad over bd plus cb over bd

What is the standard deviation of the following data set rounded to the nearest tenth? 3, 17, 18, 15, 12, 21, 9

Which data set has a greater spread? why? set a: {38, 12, 23, 48, 55, 16, 18} set b: {44, 13, 24, 12, 56} has a greater spread because .

As part of an annual fundraiser to raise money for diabetes research, diane joined a bikeathon. the track she biked on was 1,920 yards long. diane biked 38.5 laps. her sponsors agreed to donate an amount of money for each mile she biked. how many miles did she bike? first fill in the blanks on the left side using the ratios shown. then write your answer. given ratios: 5280ft / 1 mi , 1 mi /5280 ft , 1,920 yards / 1 lap , 1 lap / 1,920 yards , 3 ft / 1 yard , 1 yard / 3 ft. blanks: 38.5 laps / 1 yard x (blank) x (blank) x (blank) = (blank) miles i'm really confused on how to do this, and the explanations aren't exactly . if you could walk me through how to do this, it would be greatly appreciated.