Ineed the answer before the morning because of school hurry

22) Let w = how many weeks she needs to save. She makes 15 a week.

125 + 15w = 245

Subtract by 125 from both sides to get variables on one side of the equal sign and constants on the other.

15w = 245 - 125

15w = 120

Divide by 15 on both sides to isolate the variable w.

w = 120/15

w = 8

It will take her 8 weeks to buy the bike.

23) Let M = radius of mars. Earth's is 2981.1 km bigger.

m + 2981.1 = 6378.1

Subtract 2981.1 from both sides to get variables on one side and constants on the other.

m = 6378.1 - 2981.1

m = 3397.0

The radius of Mars is 3,397 km.

24) Let m = Maggie's age. Her brother is 3 years younger than twice her age; so 2m minus 3 years = 2m - 3

"sum... is 24" tells you to add the two together and have them equal 24.

m + 2m - 3 = 24

Combine like terms:

3m - 3 = 24

Add 3 from both sides to get variables on one side and constants on the other.

3m = 24 + 3

3m = 27

Divide by 3 to isolate the variable m

m = 27 / 3

m = 9

Maggie is 9 years old.