Hey Jessica,

Following pls find my worked solution (with reference to your attached question & figure ):

(a)

Given that 1/5 of triangle is shaded (ST), then 4/5 of triangle is Unshaded (UT). Likewise, if 2/7 of rectangle is shaded (SR), then 5/7 of rectangle is unshaded (UR).

We can express these as ratios (as shown):

** - buffer space for alignment purpose

UT : ST/SR : UR

4 * : ** 1

******* 2 ** : 5

Using <Repeated Identity> concept, we need to multiply 1st ratio 2x, as area of ST = area of SR. So we have ...

8 * : ** 2 ** : 5

Whole figure = 8u + 2u + 5u = 15u

Fraction of Whole figure shaded = **2/15**

(b)

Given area of the shaded part is 28 cm2, we have ..

2u --> 28

1u --> 14

Total area of figure = 15u --> 15 x 14 = **210 cm2**

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Trust the above helps.

Do let me know again if this does not match your Answerkey or if there's any clarification.

Cheers,

Edward