word problem

Question

a= p + prt solve for R!

 

 

If the sum and a number and two is tripled, the result is nine less than twice the number. find the number 

Answer 1

a = p + prt

 

Subtract p from both sides:

 

a - p = prt

 

Divide both sides by pt:

 

(a-p)/pt = r

 

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Let x = the unknown number.  If the sum of a number and 2 (x+2) is tripled (3(x+2)), the result is 9 less than twice the number (2x-9):

 

3(x+2) = 2x - 9

 

3x + 6 = 2x - 9

 

x = -15

 

Check:

3(-15+2) = 2(-15) - 9

3(-13) = -30 - 9

-39 = -39

Check!