Question 1105654:  Two numbers are in the ratio of 5:8 their difference is 45. What is the smaller number?  
 Answer by Theo(13342)      (Show Source): 
You can  put this solution on YOUR website! x is the first number. 
y is the second number.
 
 
x/y = 5/8 
x = 5/8 * y
 
 
y - x = 45 (because y is bigger than x, the difference will be positive).
 
 
since x = 5/8 * y , then y - x = 45 becomes y - 5/8 * y = 45 which becomes (8-5)/8 * y = 45 which becomes 3/8 * y = 45
 
 
multiply both sides of this equation by 8/3 to get y = 45 * 8/3 which results in y = 15 * 8 which results in y = 120.
 
 
when y = 120, x = 5/8 * y becomes x = 5/8 * 120 which becomes x = 5 * 15 which results in x = 75.
 
 
you have x = 75 and y = 120.
 
 
x/y = 75/120 which becomes x/y =  15/24 which becomes x/y =  5/8.
 
 
you get x/y = 5/8 which can be written as x:y = 5:8 which is what you were given to start with.
 
 
y - x = 120 - 75 = 45 which is also what you were given to start with.
 
 
the solution is confirmed to be good.
 
 
y is the biggest number. 
x is the smallest number.
 
 
the solution is that the smallest number is 75.
 
 
 
 
 
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