Answer:
The most likely solution sought is 13:
Beginning with 3: subtract 9, add 18, subtract 8, add 16, subtract 7, add 14, etc. Each time, reduce the number subtracted by one, and double that number to add.
So, beginning with 3: 3-9 = -6, -6+2(9) = 12, 12-8 = 4, 4+2(8) = 20, 20-7 = 13, etc.
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Step-by-step explanation:
Answer:
Step-by-step explanation:
1/5
Answer:
Pure water =74.1 mL
Step-by-step explanation:
You need 420 mL of a 70% alcohol solution.
420 mL of solution and 70% of it should be alcohol.
So,
420 * 70/100 mL
= 420 * 0.7
= 294 mL of alcohol and the rest should be water.
On hand, you have a 85% alcohol mixture.
The alcohol can only come from the 85% mixture. So, how much of 85% alcohol do we need to get 294 mL of alcohol:
Let
y = alcohol solution needed
85% of y = 294
85/100 * y = 294
y = 294 ÷ 85/100
y = 294 × 100/85
y = 29,400/85
y = 345.88235294117
Approximately, 345.9mL
The rest of 420 mL solution has to be pure water
Pure water = 420 mL - 345.9mL
= 74.1 mL
Pure water =74.1 mL
Divide the first fraction by 2 you get 4/11
divide the second fraction by 2 you get 6/7
