I guess the chef is making the mixture for the sheriff... Let <em>x</em> be the amount of dressing with 5% vinegar that is required, and <em>y</em> the amount of 15% vinegar dressing (both amounts in mL).
The sheriff wants 390 mL of the mixed dressing, so that
<em>x</em> + <em>y</em> = 390
<em>x</em> mL of the 5% dressing contains 0.05<em>x</em> mL of vinegar, while <em>y</em> mL of the 15% dressing contains 0.15<em>y</em> mL of vinegar. The resulting mixture should have a concentration of 9% vinegar, so that it contains 0.09 (390 mL) = 35.1 mL of vinegar. This means
0.05<em>x</em> + 0.15<em>y</em> = 35.1
Solve for <em>x</em> and <em>y</em> :
<em>y</em> = 390 - <em>x</em>
0.05<em>x</em> + 0.15 (390 - <em>x</em>) = 35.1
0.05<em>x</em> + 58.5 - 0.15<em>x</em> = 35.1
23.4 = 0.10<em>x</em>
<em>x</em> = 234
<em>y</em> = 156
3200÷100=32
Since each model is 100, you need 32 to model 3,200
Here, we can set up a proportion:
34 ÷ 3/4 = ? ÷ 1
34*1 = 34
34÷3/4 = the time needed to build one toyboat
34/3/4 = 45.3333333333
45.3 repeating is not a whole number, so we need to approximate.
45 is the closest whole number,
So.. a machine can paint 45 toy boats per hour.
I really hope that helped! :)
Breaking apart means that you just take the tens from each number, and the ones from each number, then add them up.
The tens from your numbers are:
30 from 34
40 from 45
The ones from your numbers are:
4 from 34
5 from 45
Now, you have to add up the tens and ones separately.
30 + 40 = 70
4 + 5 = 9
Finally, you add up those 2 numbers that you got- 70 and 9
The answer: Stephen read for 79 minutes total.
