PLEASE HELP 5 EIGHTH GRADE ALGEBRA MATH PROBLEMS

1.
x=2y
-9x+4y=28

2.
y=-4x+5
8x-2y=-42

3.
3x+7y=-17
-3x+9y=-15

4.
6x+12y=36
4x-6y=-4

1. what is the measure of ∠abc? what is the measure of ∠abd?

Find the least common multiple of the expressions: 1. 3x^2, 6x - 18 2. 5x, 5x(x +2) 3. x^2 - 9, x + 3 4. x^2 - 3x - 10, x + 2 explain if possible

Sarah took the advertising department from her company on a round trip to meet with a potential client. including sarah a total of 11 people took the trip. she was able to purchase coach tickets for $280 and first class tickets for $1280. she used her total budget for airfare for the trip, which was $6080. how many first class tickets did she buy? how many coach tickets did she buy?