PLEASE!!!!i need help on these 4:

Question

*4y=15-3x
2y=3x+21

*4x=5y-14
y=-6x-9

*5x=4y-30
2x=3y=-12

*2/3y=10+4x
5x=1/3y-8

use linear combinations to solve the system of linear equations

thank you!!!

Answer 1

4y=15-3x
2y=3x+21

4y=15-3x Divide with 2
2y=(15/2)-(3/2)x

2y=(15/2)-(3/2)x=3x+21

(15/2)-21=3x+(3/2)x

(15/2)-(42/2)=(6/2)x(3/2)x
-(27/2)=(9/2)x Multiply with 2
-27=9x Divide with 9
x= -3
2y=3x+21
2y=3*(-3)+21
2y= -9+21
2y= 12 Divide with 2
y=6