Part A
A tie-dye kit with one T-shirt costs $15. Each additional T-shirt costs $4 more. Choose the explicit formula to represent the situation.
A. an = 11 + 4n
B. an = 4 + 15n
C. an = 19 + 4n
D. an = 15 + 4(n + 1)
Part B
A tie-dye kit with one T-shirt costs $15. Each additional T-shirt costs $4 more. Choose the recursive formula to represent the situation.
A. an = an – 1 + 4; a1 = 11
B. an = an – 1 + 4; a1 = 15
C. an = an – 1 + 11; a1 = 15
D. an = an – 1 + 19; a1 = 11

1. 180°. the sum of the interior angles of a triangle is 180°, for the equilateral triangle that it has three equals side is 60°+60°+60°=180°.

2. 60°. each interior angle of a equilateral triangle is 60°

3. 120°. the measure of ∠m is 120°, the sum of the angles ∠m and ∠n is equal to 180°. so, in order to find the measure of ∠m, we have ∠m+∠n=180° > ∠m=180°-∠n > ∠m=180°-60°=120°.

4. 360°. the sum of the exterior angles of an equilateral triangle is ∠m+∠r+∠x=120°+120°+120°=360°. the exterior angles of any triangle always add 360°.

391.6 is the correct answer