A question:
(5.3 x 10 to the 6th power) + 8.2 10 to the 6th power)
A solution:
Multiply 10 x 10 6 times to get rid of the two powers.
(5.3 x 1,000,000) + (8.2 x 1,000,000)
Multiply inside the parenthises.
(5,300,000) + (8,200,000)
Add:
13,500,000.
A answer:
13, 500,000.
B question:
(6.5 x 10 to the 7th power) / (5 x 10 to the 3rd power)
B solution:
Again, get rid of the powers.
(6.5 x 10,000,000) / (5 x 1,000)
Multiply inside the parenthesis:
(65,000,000) / (5,000)
Divide:
13,000
B answer:
13,000.
C question:
(4.6 x 10 to the 6th power) (3 x 10 to the 5th power) / (2 x 10 to the 7th power)
C solution:
Get rid of powers:
(4.6 x 1,000,000) (3 x 100,000) / (2 x 10,000,000)
Multiply:
(4,600,000) (300,000) / (20,000,000)
multiply in the left side:
(1,380,000,000,000) / (20,000,000)
divide:
69,000
C answer:
69,000
Answer: 
Step-by-step explanation:
To find the least common multiply, you must descompose 12 and 15 into their prime factors, as you can see below:
12=2*2*3=2²*3
15=3*5
Choose the common and non common numbers with their greastest exponents:
3*5*2²=60
Now you must choose the common and non common variables with their greastest exponents:
n³
Therefore, you can conclude that the least common multiply is:

Answer:
El ancho del río es 59.9 metros.
Step-by-step explanation:
El ancho del río lo podemos calcular con la siguiente relación trigonométrica asumiendo que la torre forma un triángulo rectángulo con el río:

En donde:
CA: es el cateto adyacente = Altura de la torre = 28.2 m
CO: es el cateto opuesto = ancho del río =?
θ: es el ángulo adyacente a CA
Dado que el ángulo de depresión (25.2°) está ubicado fuera de la parte superior de la hipotenusa del triángulo que forma la torre con la orilla opuesta del río, debemos calcular el ángulo interno (θ) como sigue:

Ahora, el ancho del río es:

Por lo tanto, el ancho del río es 59.9 metros.
Espero que te sea de utilidad!