**Solution:**

Given,

2x + 3y = 11….(i)

2x – 4y = -24….(ii)

From equation (ii), we get;

x = (11-3y)/2 ….(iii)

Substituting the value of x in equation (ii), we get;

2(11-3y)/2 – 4y = 24

11 – 3y – 4y = -24

-7y = -35

y = 5 ….(iv)

Putting the value of y in equation (iii), we get;

x = (11 – 3 × 5)/2 = -4/2 = -2

Hence, x = -2, y = 5

Also,

y = mx + 3

5 = -2m +3

-2m = 2

m = -1

**Therefore, the value of m is -1.**