The function
may be used to model radioactive decay. Q
represents the quantity remaining after tyears; k is the decay constant. What
is the decay constant for plutonium-240 if its half-life is 6,300 years?

so, converting firstly the mixed fractions to improper fractions and then "adding".

step-by-step explanation:

the ratio of red paint to blue paint is always 9/7. that means that, whatever x's value, (4x+12)/(4x-4) has that same ratio. so, set up an equation and cross-multiply to solve for x:

9/7 = (4x+12)/(4x-4)

9(4x-4) = 7(4x+12)

36x - 36 = 28x + 84

8x - 36 = 84

8x = 120

x = 15