- 4x + 25 = 13
4x = 12
x = 3
Answer:
The equation not represent a proportional relationship because the line don't passes through the origin
Step-by-step explanation:
we know that
A relationship between two variables, x, and y, represent a proportional variation if it can be expressed in the form
or
In a proportional relationship the constant of proportionality k is equal to the slope m of the line <u><em>and the line passes through the origin</em></u>
so
In this problem we have

This is the equation of the line in slope intercept form
where
the slope is m=5
the y-intercept is b=5
Remember that in a proportional relationship the value of b must be equal to zero (because the line passes through the origin)
therefore
The equation not represent a proportional relationship because the line don't passes through the origin
<span>60.5 milligrams per square centimeter
First, determine how many half lives have expired by dividing the time by the half-life. So:
55/20 = 2.75
That means that only 2^(-2.75) = 0.148650889 = 14.8650889% of the original substance remains. So just divide the amount remaining by 0.148650889 to get the original amount.
9 / 0.148650889 = 60.5445419
So originally, there was 60.5 milligrams per square centimeter 55 years ago.</span>