(A) . The inequality is - 3x < 30 + 2x.
\Subtract 2x from each side.
\- 3x - 2x < 30 + 2x - 2x
\- 5x < 30
\Divide each side by negative 5 and reverse the inequality symbol.
\(- 5x) / (- 5) > (5*6) / (- 5)
\Cancel common terms.
\x > - 6.
\(B) . The inequality is x + 3 ≥ 6(x - 4) +7.
\Apply distributive property : a(b - c) = ab - ac.
\x + 3 ≥ 6x - 24 +7
\x + 3 ≥ 6x - 17
\Subtract 3 from each side.
\x + 3 - 3 ≥ 6x - 17 - 3
\x ≥ 6x - 20
\Subtract 6x from each side.
\x - 6x ≥ 6x - 20 - 6x
\- 5x ≥ - 20
\Divide each side by negative 5 and reverse the inequality symbol.
\(- 5x) / (- 5) ≤ (- 5*4) / (- 5)
\Cancel common terms.
\x ≤ 4.
\The formula for the perimeter of the rectangle P = 2(l + w), where l = length and w = width.
\Let x be the length(l) of the rectangle.
\The width(w) of the rectangle = 4 ft shorter than the length = x - 4.
\The perimeter(P) of the rectangle is greater than 72 ft ⇒ P > 72.
\2(l + w) > 72
\2[ x + (x - 4) ] > 72
\x + (x - 4) > 36
\2x - 4 > 36
\2x > 40
\x > 20.
\The length(l) of the rectangle is greater than 20 ft ⇒ x > 20.
\Subtract 4 from each side of the above inequality.
\x - 4 > 20 - 4
\x > 16.
\The width(w) of the rectangle is greater than 16 ft ⇒ x > 16.
\Length : x > 20 and Width : x > 16.