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

In what form is the following linear equation written y=9x+2

What is the solution to the system of equations? (–2, –8) (–1, –5) (0, –2) (2, 4)

He weights of 2-pound bags of best dog food are approximately normally distributed with a given mean  and standard deviation  according to the empirical rule, what percentage of the bags will have weights within 3 standard deviations of the mean? 47.5%68%95%99.7%