Answer:
Step-by-step explanation:
60 minutes divided by 5 times 8
96 feet
So, the first brand has 9% vinegar, and say we use "x" amount of it, then, the amount of vinegar in "x" is 9% of x, or (9/100) * x, 0.09x.
the second brand has 14% of vinegar, and if we use say "y" amount of it, then the amount of vinegar in "y" is really just 14% of "y" or, (14/100) * y, 0.14y.
![\bf \begin{array}{lccclll} &\stackrel{mL}{amount}&\stackrel{\%}{concentration}&\stackrel{amount}{concentration}\\ &------&------&------\\ \textit{first brand}&x&0.09&0.09x\\ \textit{second brand}&y&0.14&0.14y\\ ------&------&------&------\\ mixture&230&0.13&29.9 \end{array}](https://tex.z-dn.net/?f=%5Cbf%20%5Cbegin%7Barray%7D%7Blccclll%7D%0A%26%5Cstackrel%7BmL%7D%7Bamount%7D%26%5Cstackrel%7B%5C%25%7D%7Bconcentration%7D%26%5Cstackrel%7Bamount%7D%7Bconcentration%7D%5C%5C%0A%26------%26------%26------%5C%5C%0A%5Ctextit%7Bfirst%20brand%7D%26x%260.09%260.09x%5C%5C%0A%5Ctextit%7Bsecond%20brand%7D%26y%260.14%260.14y%5C%5C%0A------%26------%26------%26------%5C%5C%0Amixture%26230%260.13%2629.9%0A%5Cend%7Barray%7D)
so, whatever "x" and "y" are, we know that
x + y = 230.
and we also know that their concentration amounts will also add up,
0.09x + 0.14y = 29.9.
![\bf \begin{cases} x+y=230\implies \boxed{y}=230-x\\ 0.09x+0.14y=29.9\\ ----------\\ 0.09x+0.14\left(\boxed{230-x} \right)=29.9 \end{cases} \\\\\\ 0.09x+32.2-0.14x=29.9\implies -0.05x=-2.3\implies x=\cfrac{-2.3}{-0.05} \\\\\\ x=46](https://tex.z-dn.net/?f=%5Cbf%20%5Cbegin%7Bcases%7D%0Ax%2By%3D230%5Cimplies%20%5Cboxed%7By%7D%3D230-x%5C%5C%0A0.09x%2B0.14y%3D29.9%5C%5C%0A----------%5C%5C%0A0.09x%2B0.14%5Cleft%28%5Cboxed%7B230-x%7D%20%20%5Cright%29%3D29.9%0A%5Cend%7Bcases%7D%0A%5C%5C%5C%5C%5C%5C%0A0.09x%2B32.2-0.14x%3D29.9%5Cimplies%20-0.05x%3D-2.3%5Cimplies%20x%3D%5Ccfrac%7B-2.3%7D%7B-0.05%7D%0A%5C%5C%5C%5C%5C%5C%0Ax%3D46)
how many milliliters will it be for the second brand? well, y = 230 - x.
Last week, Christopher drove 480 miles
This week, Christopher drove 360 miles
The difference in miles this week compared to last week = 480 - 360 = 120 miles.
The percentage of decrease in miles compared to last week's = (Difference in miles ÷ Total miles last week) multiplied by 100 = (120 ÷ 480) x 100 = 0.25 x 100 = 25%
The answer can be found by subtract the volume of the small box from the volume of big box.
Volume of the small box:
12*8*4= 384 inches cube
Volume of the big box:
20*15*9= 2700 inches cube
The space left:
2700 - 384 = 2316 inches cube