Can someone answer this algebraically?

Question

If a physician orders 25% dextrose, 1000 mL and all you have is 70% dextrose 1,000 mL, how much 70% dextrose and how much sterile water will be used?  Please help me with this.  My professor did not explain this to us.

Answer 1

Think in terms of water!

You want a 75% solution of water, yet

only have a 30% solution of water

 

0.30(1000 - w) + w = 0.75(1000 + w)

 

Can you solve for w and answer?