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3 years ago

HELP PLS SHOW WORK ITS 2 PARTS

Mathematics

2 answers:

sdas [7]3 years ago

7 0

Answer:

a=4.2

Step-by-step explanation:

6.4-a=2.2

so 6.4-22=a

4.2=a

jok3333 [9.3K]3 years ago

6 0

Answer:

Step-by-step explanation:

6.4 - 2.2 = 4.2

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The sum of reciprocals of rehman’s ages 3 years ago and 5 years from now is 1/3. Find his present age

Afina-wow [57]

Answer:

His age is 7 years.

Step-by-step explanation:

Let Rehman's present age be x years.

1 / (x - 3) + 1 /(x + 5) = 1/3

Multiply through by the LCD 3(x - 3)(x + 5):

3(x + 5) + 3(x - 3) = (x + 5)(x - 3)

3x + 15 + 3x - 9 = x^2 + 2x - 15

x^2 + 2x - 6x - 30 + 9 = 0

x^2 - 4x - 21 = 0

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x = 7 (answer).

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3 years ago

The height of a 12-year-old boy increased by 17% last year and by 12% this year. What is the total increase in percentage terms?

murzikaleks [220]

Answer:

1. 12(1.17h) = 1.3104h Which is a 31.04% increase

Step-by-step explanation:

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3 years ago

How much money was taken off the 1000RM loan for every child born to

grigory [225]

Answer:

Step-by-step explanation:i have no clue

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3 years ago

Factor 80t - 16t = 0<br><br> help?

Alinara [238K]

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3 years ago

Assume you have such a watch. if a minimum of 18.0% of the original tritium is needed to read the dial in dark places, for how m

laila [671]

Given that the half life of 3H is 12.3 years.

The amount of substance left of a radioactive substance with half life of $t_{ \frac{1}{2} }$ after t years is given by

$N(t)=N_0\left(\frac{1}{2} \right)^{ \frac{t}{t_{\frac{1}{2}} }$

Therefore, the number of years it will take for 18% of the original tritinum to remain is given by

$18 \% = 100 \% \left(\frac{1}{2} \right)^{ \frac{t}{12.3}} \\ \\ \Rightarrow\left(\frac{1}{2} \right)^{ \frac{t}{12.3}} =0.18 \\ \\ \Rightarrow\frac{t}{12.3}\ln\left(\frac{1}{2} \right)=\ln0.18 \\ \\ \Rightarrow\frac{t}{12.3}= \frac{\ln0.18}{\ln\left(\frac{1}{2} \right)} = \frac{-1.715}{-0.6931} =2.474\\ \\ \Rightarrow t=2.474(12.3)=30.4$

Therefore, the number of <span>years that the time could be read at night is 30.4 years.</span>

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3 years ago