Answer:
<em>102°</em>
Step-by-step explanation:
(3x - 12)° + (2x + 2)° = 180°
5x - 10 = 180 ⇒ x = 38
m∠A = (3x - 12)°
<em>m∠A</em> = (3×38 - 12)° = <em>102°</em>
There are 4 cards facing up and the rest facing down
Answer:
see explanation
Step-by-step explanation:
the sum to n terms of an arithmetic sequence is
=
[2a + (n - 1)d ]
where d is the common difference and a is the first term
here d = 9 - 7 = 7 - 5 = 2 and a = 5, hence
=
[(2 × 5) + 2(n - 1) ]
=
(10 + 2n - 2)
=
(2n + 8)
= n² + 4n
When sum = 165, then
n² + 4n = 165 ← rearrange into standard form
n² + 4n - 165 = 0 ← in standard form
(n + 15)(n - 11) = 0 ← in factored form
equate each factor to zero and solve for n
n + 15 = 0 ⇒ n = - 15
n - 11 = 0 ⇒ n = 11
but n > 0 ⇒ n = 11
Tough one give me a couple min.