Question 663429
Starting with 
4/6 = x + 8/15
First isolate the x
x = 4/6 - 8/15
Then apply common denominators to your fractions
x = 4/6(5/5) - 8/15(2/2)
x = 20/30 - 16/30
Now you can subtract and simplify
x = 4/30 = 2/15
Post more if you have more questions and need further clarity.
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