Answer:
(2/5)*b+1 = -11 // + 11
(2/5)*b+1+11 = 0
2/5*b+12 = 0 // - 12
2/5*b = -12 // : 2/5
b = -12/2/5
b = -30
b = -30
Step-by-step explanation:
hope this helped :)
Answer:
3.6 hours
Step-by-step explanation:
To solve, create a Rate, Time, Work chart:
Work is rate times time. For Kevin, his work is going to equal x over 6 job. For Anna, her expression for work will equal x over 9 job.
The work is 1 job of calling all clients, so their combined work is equal to 1.
x over 6 plus x over 9 equals 1
In the rational equation, x is the amount of time it takes Kevin and Anna to call the clients together. With rational equations, the terms can be added together once they have common denominators.
x over 6 plus x over 9 equals 1
fraction numerator begin display style x left parenthesis 9 right parenthesis end style over denominator begin display style 6 left parenthesis 9 right parenthesis end style end fraction plus fraction numerator begin display style x left parenthesis 6 right parenthesis end style over denominator begin display style 9 left parenthesis 6 right parenthesis end style end fraction equals fraction numerator begin display style 1 left parenthesis 6 right parenthesis left parenthesis 9 right parenthesis end style over denominator left parenthesis 6 right parenthesis left parenthesis 9 right parenthesis end fraction
fraction numerator 9 x over denominator 54 end fraction plus fraction numerator 6 x over denominator 54 end fraction equals 54 over 54
9 x plus 6 x equals 54
15 x equals 54
x equals 3.6
If Kevin and Anna work together, they can call all the clients in 3.6 hours.
Multiply all terms by 15
3x+3x= 10x+30
Combine like terms
6x=10x+30
Subtract 10x from both sides
-4x=30
Divide both sides by -4
x= -7.5
Final answer: -7.5
Answer:
im probably wrong but i think it's C
For this case we have an equation of the form:
y = A * (b) ^ t
Where,
A: initial amount
b: decrease rate
t: time in years.
Substituting values we have:
7 = A * (0.5) ^ ((1/20) * t)
For t = 45 years we have:
7 = A * (0.5) ^ ((1/20) * 45)
Clearing A:
A = 7 / ((0.5) ^ ((1/20) * 45))
A = 33.3
Answer:
the density of the substance when it was deposited 45 years ago was:
A = 33.3 milligrams per square centimeter