solve using substitution:

Question

4x+9y=24
y=1/3x+2

Answer 1

y = ( 1 / 3 ) x + 2

4 x + 9 y = 24

4 x + 9 [ ( 1 / 3 ) x + 2 ] = 24

4 x + ( 9 / 3 ) x + 18 = 24

4 x + 3 x + 18 = 24

7 x + 18 = 24 Subtract 18 to both sides

7 x - 18 = 24 - 18

7 x = 6 Divide both sides by 7

x = 6 / 7

y = ( 1 / 3 ) x + 2

y = ( 1 / 3 ) 6 / 7 + 2

y = 1 * 6 / ( 3 * 7 ) + 2

y = 6 / 21 + 2

y = 6 / 21 + 42 / 21

y = 48 / 21

y = 3 * 16 / ( 3 * 7 )

y = 16 / 7

Answer 2

You posted the same question 3 times within about 20 minutes, causing an unnecessary duplication in a solution.
Have patience.