If X : Y=1 : 5, then what is the value of X : (X + Y)?

Given: 

X : Y = 1 : 5 

Solution: 

Let X = 1t, Y = 5t 

Now, 

​$$\frac{X}{X+Y} = \frac{1t}{1t+ 5t} = \frac{1t}{6t} = \frac{1}{6}$$ 

Thus, the ratio of X : (X + Y) = 1 : 6 ​​