If the soloist produces "x" decibels and the 10-person choir produces "y" decibels, combined they will produce "x+y" decibels. 
The second choir has 90 additional singers, we base our description on the first choir. If a 10-person choir produces "x+y" decibels, then the 90 person choir produces 10 (x+y) decibels. 
        
             
        
        
        
The SI unit of length or distance is the meter.
        
             
        
        
        
-- The acceleration due to gravity is 32.2 ft/sec² .  That  means that the 
speed of a falling object increases by an additional 32.2 ft/sec every second.
-- If dropped from "rest" (zero initial speed), then after falling for 4 seconds, 
the object's speed is (4.0) x (32.2) = <em>128.8 ft/sec</em>.
-- 128.8 ft/sec = <em>87.8 miles per hour</em>
Now we can switch over to the metric system, where the acceleration 
due to gravity is typically rounded to 9.8 meters/sec² .
-- Distance = (1/2) x (acceleration) x (time)²
       D = (1/2) (9.8) x (4)² =<em>  78.4 meters</em>
-- At 32 floors per 100 meters,  78.4 meters = dropped from the <em>25th floor</em>.
The 5 points are certainly appreciated, but I do wish they were Celsius points.
        
             
        
        
        
Answer: 
The electric field strength at the midpoint of the line joining the charges is zero (0)
Explanation:
Given that the two charges are both positive (same charge) and are equal in magnitude that is 6uC. The electric field strength at the midpoint of the line joining the two charges will be equal and opposite in magnitude, therefore they will cancel each other out and the electric field strength at this point will be equal to zero.