What does this mean? Assuming you're talking about listening to the song on a computer, you'd be using a software.
Exactly 80 liters of 20% are needed.
Let quantity of 20% alcohol solution be added : x liters
Here is the work:
> x*20% + 40 * 50% = (x+40) * 30%
> x*0.2 + 40*0.5 = (x+40)*0.3 ..(converting percentages into decimal)
> 0.2x + 20 = 0.3x + 12
> 20-12 = 0.3x - 0.2x (Rearranging similar terms)
> 8 = 0.1 x
Hence x = 8/0.1
Ans 80 Litres
By Newton's second law, the net force on the object is
∑ F = 10.0 N + F = (7.0 kg) (1.0 m/s²)
where F is the unknown force. Since the object is accelerating to the east, F must be acting in the same or opposite direction as the known force that is also directed eastward. Solve for F :
10.0 N + F = 7.0 N
⇒ F = - 3.0 N
which is to say, F has magnitude 3.0 N and points toward the west.
