You would want to buy 8 boxes for 30$
89.95 x 0.05 (5%)
=4.4975
The final cost of the DVD player is 89.95-4.4975
=85.4525
≈ $85.45
A) The first step needs 100 bricks, the second needs 98, the third needs 96, and so on. Therefore the number of bricks for the nth step is: a_n = a_1 + d(n-1), where a_1 = 100 (the first term), d = -2 (difference).
a_n = 100 - 2(n-1) = 102 - 2n, and for the 30th step, a_30 = 102 - 2*30 = 42. So the top step will need 42 bricks.
b) The total staircase will need: 100 + 98 + 96 + ... + 44 + 42, and there are n = 30 terms. Using the formula for the sum of an arithmetic sequence:
S = (a_1 + a_n)*n/2 = (100 + 42)*30/2 = 2130
Therefore, 2130 bricks are required to build the entire staircase.
(AAA) Corresponding angles are congruent.
Therefore, the sides of the triangles are proportional:
cross multiply
use distributive property
subtract 100 from both sides
divide both sides by 100

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(SAS)
If two sides and the included angle of one triangle are equal to the corresponding sides and angle of another triangle, the triangles are congruent.
Therefore we have the equation:

The perimeter of △PQR:

Substitute the value of y to the expression:
