Linear equation

Question

A scientist mixes water (containing no salt) with a solution that contains 45% salt. She wants to obtain a mixture that is 20% salt. How many ounces of water and how many ounces of the 45% salt solution should she use?

Answer 1

45-20=25

she needs more water than 45% salt

25/20=5/4 times more

5 ounces of water with every 4 ounces of 45% salt yield a mixture of 9 ounces of 20% salt

5(.0)+4(.45)=9(.2)=1.8 ounces of pure salt & 7.2 ounces pure water