SOLUTION: one number is 3 times another number.If 15 is added to the both the numbers,then one of the new numbers becomes twice that of the other new number.Find the number.

Question 1039514: one number is 3 times another number.If 15 is added to the both the numbers,then one of the new numbers becomes twice that of the other new number.Find the number.
Answer by Theo(13342) (Show Source): You can put this solution on YOUR website!
let a = one of the numbers.
let b = the other number.
you get a = 3b
add 15 to and b, and it becomes 2 * b.
you get a + 15 = 2 * (b + 15)
since a = 3b, replace a in the last equation with 3b to get 3b + 15 = 2 * (b + 15).
simplify to get 3b + 15 = 2b + 30
subtract 2b from both sides of the equation and subtract 15 from both sides of the equation to get:
3b - 2b = 30 - 15
simplify to get b = 15.
since a = 3b, then a = 45.
a = 3b becomes 45 = 3*15 which is true.
a + 15 = 2 * (b + 15) becomes 45 + 15 = 2 * (15 + 15) which becomes 60 = 2 * 30 which is true.
looks like the solution is good.
a = 45
b = 15.
the number is 45.

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