Answer:
a=-8
Step-by-step explanation:
The Given equation is , 3 x + x = 440,
Let speed of train A is x Km/hour and Speed of train B which is a Bullet train which starts from same station but from different platform is 3 times the speed of train A.
And Sum of their Velocities is i.e Velocity of train A and Velocity of train B is 440 Km/hour.
You are inversing for subtraction which is addition so D
Answer: 
Step-by-step explanation:
1. By definition, scientific notation has the following form:
Where:
<em> a</em> is a number between 1 and 10 but does not include 10.
<em> b </em>an integer.
2. When you multiply 3.25 by 7.8 the result is 25.35 and when you multiply 
by 
, you obtain 
, but to write ree thsult in scientific notation, the decimal point must be after the first digit. Therefore, you must move the decimal point one place to the left. So, the exponent changes from 9 to 10:
4a+9=(-9+30-25). 4a+9=30-34. 4a+9=-4. 4a=-13. A=-3.25 :)
