Answer: "Count 2 and then count 31 more."
Step-by-step explanation:
We have the equation:
231 - 198
Now, the negative number is kinda ugly, so i will write it as:
200 - 2 = 198
Is a lot easier work with 200 and 2, than with 198.
Then the equation is now:
231 - (200 - 2)
And the left number we also have a "200", so it can be written as:
200 + 31 = 231
As this is a sum, we can ignore the parentheses.
200 + 31 - 200 + 2
31 + 2
Then the correct option is:
"Count 2 and then count 31 more."
5,000
is 300 closer to 100 or 1000?
or
is 3 closer to 1 or 10?
Answer:
50
Step-by-step explanation:
[15 ÷ 5 • 3 + (2³ – 3)] + [4 • (36 – 3³)]
[3 × 3 + (8 - 3)] + [4 × (36 - 27)]
(9 + 5) + (4 × 9)
14 + 36
50
Are you rounding to the nearest 100’s place?
Answer:
the chemist should use 60 liters of 55% solution and 40 litres of 30% solution in order to prepare 100 liters of 45% purity of sulphuric acid.
Step-by-step explanation:
From the given information,
Let x be the litres of 55% pure solution
Let y be the litres of 30% pure solution
Also;
Given that our total volume of solution is 100 litres
x+y =100 ---- (1)
The total solution of pure by related by the sum of the individual pure concentrations to make up the concentration of final solution.
(0.55)(x)+(0.30)(y) = 0.45(100) ---- (2)
From equation (1)
Let ; y = 100 - x
Replacing the value for y = 100 - x into equation (2)
(0.55)(x)+(0.30)(100-x) = 0.45(100)
0.55x + 30 - 0.30x = 45
0.55x - 0.30x = 45 - 30
0.25x = 15
x = 15/0.25
x = 60 liters of 55% solution
From ; y = 100 - x
y = 100 - 60
y = 40 litres of 30% solution.
Therefore, the chemist should use 60 liters of 55% solution and 40 litres of 30% solution in order to prepare 100 liters of 45% purity of sulphuric acid.
