Answer:
Y = 32.7°
Step-by-step explanation:
We will apply the Cosine law in the given triangle XYZ,
x = 90 ft
y = 55 ft
z = 50 ft
We have to find the measure of angle Y.
y² = x² + z² - 2xzCosY
(55)² = (90)² + (50)² - 2(90)(50)cosY
3025 = 8100 + 2500 - 9000.cosY
9000.cosY = 10600 - 3025
cosY = 
= 0.84167
Y = 
Y = 32.68 ≈ 32.7°
Therefore, measure of angle Y = 32.7°
The square of a binomial expands as follows:

Expanding all the binomials, we have

Sum like terms:

Simplify terms appearing on both sides:

Move all terms involving k to the left and all numbers to the right:

Divide both sides by -20:

Surface of a cubical box=6(side²)
1)We have to calculate the surface of this cubical box.
Rate=cost of painting / surface ⇒surface=cost of painting/rate
Data:
Rate=$15/m²
cost of painting=$1440
Surface=$1440/($15/m²)=96 m²
2)We find out the length of the side:
Surface of a cubical box=6(side²)
Data:
Surface of a cubical box=96 m2
Therefore:
96m²=6 (side²)
side²=96 m²/6
side²=16 m²
side=√(16 m²)=4 m
3) We find the volume of a cubical box.
volume=(side³)
volume=(4 m)³
volume=64 m³
Answer: the volume of this cubical box would be 64 m³.
-2 (-30) - 3y = 42
60 - 3y = 42
-3y = -18
y = 6