Create an expression to find the time for the given distance and rate, and find the value of the expression. d=84 feet; r=12 feet/seconds

Note the equation/formula:
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         d * r = t  ;
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  in which:  
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        d = distance = 84 ft.
        r  = rate = 12 ft / sec
        t  = time = ?
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To find the "time" we can rearrange the equation:
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       d = r * t  ;   
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   Divide EACH SIDE of the equation by "r" ;  to isolation "t" on one side of the equation; to create an expression to find the time for the given distance and rate; which we will then do by plugging in our given values for "d" (distance) and "r" (rate) ;
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     d / r = (r * t) / r ;  
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 to get :   d / r = t ; 
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         ↔   t = d / r  ;
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Now, plug in our given values for "d" and "r" ; to solve for "t" ;
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        →    t = 84 ft / (12 ft / sec) ; 
   
                  =  84 ft   ÷    ;
    
                  =  84 ft  *   ;
  
                  =  {   }  sec. ;
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                    →   t    =   7 sec.   {that is;  "7 seconds" }.
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Answer: b 2 = 1.

step-by-step explanation: given equation a = h(b 1+b 2)

also we are given values of a, h and b 1 as :

a = 16, h = 4, and b 1 = 3.

in order to solve it for b 2, we need to plug the given values of   a, h and b 1 .

therefore, plugging values of   a, h and b 1   in given equation, we get

16 = 4( 3 + b 2)

first dividing both sides by 4, we get

4 = 3 + b 2

subtracting 3 from both sides, we get

4 -3 = 3 -3 + b 2

1 = b 2.

therefore, b 2= 1.