Question

solve by cross multiplication: 3x+y=13 and x-3y+9=0​

Answer 1

Answer:

3x+y=13 ----(1)

x-3y= -9 -----(2)

multiply equ^n 1 by 2 and equ^n 2 by 6

6x+2y=26

6x-18y= -54 change sign

- + +

20y= 80

y= 4

put the value of y = 4 in equation 1

3x+4= 13

3x = 13-4

3x = 9

x = 3