Answer:

• x = 7

Step-by-step explanation:

Complementary angles are angles that add up to 90°.

We have C and D as complementary.

Their sum is:

• m∠C + m∠D = 90

Substitute values and solve for x:

• 8x + 5x - 1 = 90
• 13x = 90 + 1
• 13x = 91
• x = 91/13
• x = 7

Answer:

x = 7

Step-by-step explanation:

Complementary angles are two angles that sum up to 90°. In this case, we are given that ∠C and ∠D are complementary. This means that the sum of ∠C and ∠D is equivalent to 90°.

⇒ ∠C + ∠D = 90°

⇒ 8x + 5x - 1 = 90°                                                          [∠C = 8x; ∠D = 5x - 1]

⇒ 13x - 1 = 90°

⇒ 13x = 90 + 1

⇒ 13x = 91

⇒ 13x/13 = 91/13

⇒ x = 91/13 = 7