Explanation:
this is a 14.4 in × 10.2 in rectangle, were 2 identical half-circles (= 1 full circle) are removed.
so, in other words, the shaded area is
rectangle area - circle area
the rectangle area is length × width.
the circle area is pi×r². with r (radius) being half the diameter. the diameter is 10.2 in, so, r = 10.2/2 = 5.1 in.
so, the shaded area is
14.4 × 10.2 - pi × 5.1² = 146.88 - 3.14 × 26.01 =
= 146.88 - 81.6714 = 65.2086 ≈ 65.21 in²
remember, an area is always expressed in square units. a volume in cubic units. and a length in simple units.