Question 1127810
You want to get 150 gallons of a 50​% solution
Let the 10​% solution be x
Since you want 150 g. total, the amount of solution at 60% will be 150 - x
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0.10x + 0.60(150 - x) = 0.50(150)
0.10x + 90 - 0.60x = 75
-0.50x = -15 
x = 30
you need 30 gallons of the 10% solution and 150-30 = 120 gallons of the 60% solution.