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

The marked price of an article is 25% above its selling price and the cost price is 30% less than its marked price . find the discount percent and gain percent. only a brainlest can solve it i will mark you brainlest

Pls what is the decimal equivalent of 5 over 9? select one: a. 0 point 5 bar over top of 5 b. 0 point 6 bar over top of 6 c. 0 point 8 bar over top of 8 d. 0 point 9 bar over top of 9

Use corrrct notations to name the sides