I have 450 grams of salt and flour mix. How many grams of flour should I add to reduce the percentage of salt in the mixture to 90% of what it was?
(a) 50
(b) 10
(c) 30
(d) 45
(e) 60
You want to add x grams of flour to the 450 grams of salt. Thus you will have a total mass of 450 + x grams. This will make the amount of salt be 90% of the total so: <-- Cross multiply