How many liters of a 12% salt solution must be added to 10 liters of a 25% salt solution to get a 20% salt solution ?

There must be added 6.25L of a 12% salt solution

Step-by-step explanation:

We add  ‘x’ litres of 12% salt solution into 10 litres of 25% salt solution, so resulting in “x+10” litres of 20% salt solution.

x litres  of 12% salt solution  + 10 litres 25% salt solution = (x+10) litres 20% salt solution

this gives us the formula:  

x(12) + 10(25) = (x+10)20

12x + 250 = 20x +200

-8x = -50

x=6.25

Therefore add 6.25 litres of 12% salt solution to 10 litres of 25% salt solution to obtain a 20% salt solution.

1/5^2 = 7.56/45

answer: city needs 2.4 inches of rainfall more to match the record of 40 inches.

step-by-step explanation:

since we have given that

total annual rainfall a city record = 40 inches

this year, total rainfall recorded = 37.6 inches

number of inches of rainfall   is needed to match the record of 40 inches is given by

hence, city needs 2.4 inches of rainfall more to match the record of 40 inches.