Moonshine Problem: How many gallons of 20% moonshine and how many gallons of 30% moonshine have to be mixed together to make 100 gallons of 25% moonshine? (x = gallons of 20% moonshine; y = gallons of 30% moonshine. 20% moonshine is called 20% because 20% of any amount (like x) is PURE MOONSHINE!)

50 gallons 20%

50 gallons 30%

Step-by-step explanation:

If x is gallons of 20% moonshine, and y is gallons of 30% moonshine, then:

x + y = 100

0.20x + 0.30y = 0.25(100)

Solve the system of equations using substitution or elimination.  Using substitution:

0.20x + 0.30(100 − x) = 0.25(100)

0.20x + 30 − 0.30x = 25

5 = 0.10x

x = 50

y = 50

step-by-step explanation:

descending order means to order the polynomials from the term with the largest exponent to the term with the smallest exponent.  

therefore, the correct answer is d.