The amount of the substance decreases by 20%
20
%
each week for a number of weeks,
w
. the expression 100(1−0.2)
100
1
-
0
.
2
w
finds the amount of radioactive substance remaining after
w
weeks. which statement about this expression is true?

what is all that apply?

step-by-step explanation:

to find if any function is an inverse of the other, put the first equation in as x in the next one. then simplify and solve. if at the end you get the statement y = x, then it is an inverse. if you get anything else, it is not.

this is a direct variation proportion. y = kx

y is the total amount due, k is the constant of variation, and x is the number of texts sent.

plug in the 3.20 and the 16 to solve for the "k". this is the constant of proportionality. it is the value that will not change.

3.20 = k(16). solving you get $.20 per text.

the equation would then be y = .20x

a 90 degree rotation across the the origin followed by a reflection across the x-axis.

step-by-step explanation: