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Times -7 by everything in the parentheses. so
-7 times 5y=-35y
-7 times -2u=14u
-7 times -5 = 35
therefore 35y+14u+35
The frustum can be considered as consisting of a square pyramid, less the
cut volume.
- The mass of the stand, is approximately 18.60905 kg
Reasons:
The given parameter of the frustum are;
The density of the frustum, ρ = 85 g/cm³
Height of pyramid, h = 9 cm
Side length of base = 10 cm
Height of frustum
By proportional shapes, the side length of the top of the frustum can be found as follows;



B₁ = 10², B₂ = 
Therefore;

The volume of the stand, V ≈ 218.93 cm³
Mass = Volume × Density
∴ Mass of the stand, m = 218.93 cm³ × 85 g/cm³ = 18,609.05 grams = 18.60905 kg.
Learn more here:
brainly.com/question/24323975
Step-by-step explanation:
The expressions are not properly written
Given
RS = 4x – 9
ST = 19
RT = 8x – 14
Based on the given parameters, the addition postulate below is true
RS+ST = RT
Substitute
4x-9+19 = 8x-14
collect like terms
4x-8x = -14-19+9
-4x = -33+9
-4x = -24
x = -24/-4
x = 6
Get RS:
RS = 4x-9
RS = 4(6)- 9
RS = 24-9
RS = 15
Get RT:
RT = 8x - 14
RT = 8(6)-14
RT = 48-14
RT = 34
T.S.A. = pi (7) (24) + pi (7)^2 = 168pi + 49pi = 217 pi cm^2 = more or less 681,73 cm^2