The are of P+Q is 10 cm square. Which is (1/6 +1/9 ) = 5/18 of the square area.

To calculate the full area of the square. It is 10 ÷ 5/18 = 36 cm square.

Based on that square length and breadth is the same. Square root of 36 is 6cm

The side of the square is 6 cm.

Qn 2.

If you look at the triangle formed by P and S. You get a triangle that has the same length and base of 6 cm.

So the area of P + S is 36 /2 = 18 cm square.
Area of P is 36 × 1/9 = 4 cm square.

Area of S is 18 - 4 = 14 cm square.

Fraction of S in the square = 14 /36 = 7 /18