Missing info

Meaning cannot be solve?

It can be solved.

WP = PX so the line PQ divides the rectangle WXYZ into two equal parts.

(The question probably intended to label YQ and QZ as equal lengths as well but it might have been omitted by accident)

The idea is that PQ = WZ = XY and the 3 lines are all parallel to each other.

Your annotation in the diagram is correct.


Info we need to use to solve :

WP = PX = ZQ = QY

(we basically have two identical rectangles forming the big rectangle. Each rectangle's area is half the area of the big rectangle)


Next,

Area of △ A + Area of △ B + Area of △ ​C

= ½ × height of △A × base of △A
+ ½ × height of △B × base of △B
+ ½ × height of △C × base of △C

= ½ × WP × base of △A
+ ½ × QY × base of △B
+ ½ × QY × base of △C

= ½ × QY × base of △A (since QY = WP)
+ ½ × QY × base of △B
+ ½ × QY × base of △C


= ½ × QY × (base of △A + base of △B + base of △C)

= ½ × QY × PQ

= ½ × area of one of the small rectangles (PXYQ)

= ½ × ½ × Area of rectangle WXYZ

= ¼ × Area of rectangle WXYZ

Now, ¼ of the area of WXYZ is the same as saying 25% of the area of WXYZ

(Recall conversion of percentage to fractions 25% of ___ = 25/100 of ___ = ¼ of ___)


So, given the combined area of △B and△C is 17% of WXYZ's area,

And, having found that the combined area of all 3△s is 25% of WXYZ's area,

Then , we can deduce that the area of △A is (25% - 17%) of WXYZ's area

= 8% of WXYZ's area


So 8% of WXYZ's area = 256cm²

1% of WXYZ's area = 256cm² ÷ 8 = 64cm²



Now the combined area of all 3 △s (shaded part) is 25% of WYXZ's area .


So area of unshaded parts must be (100% - 25%) of WXYZ's area

= 75% of WXYZ's area

= 64cm² × 75

= 4800 cm²

Edit :


It should be :

1% of WXYZ's area = 256cm² ÷ 8 = 32cm², and not 64cm²

Then,

Unshaded area = 32cm² × 75 = 2400cm²