Let x be the square meters of material used to make 1 cloak and y be the square meters of material used to make 1 dress
We have these equations :
2x + 3y = 9.6 multiply through by -4 ⇒ -8x - 12y = -38.4 (1)
3x + 4y = 13.3 multiply through by 3 ⇒ 9x + 12y = 39.9 (2)
Add (1) and (2) and we get that
x = 1.5 = the square meters of material needed to make one cloak
And the number of square meters to make one dress can be found thusly :
2 (1.5) + 3(y) = 9.6
3 + 3y = 9.6 subtract 3 from both sides
3y = 6.6 divide both sides by 3
y = 2.2 = the square meters of material needed to make one dress