Hope these help:
#9
a-4 divided by 5 = 12
5*12 is 60
60+4 is 64
60 (final answer for a)
#10
n+3 divided by 8 = -4
8*(-4) = -32
-32 + 3 = -35
-32 (final answer for n)
#11
6+z divided by 10 = -2
-2 * 10 = -20
-20=6=-26
-20 (final answer for z)
btw, can't see diagram
Answer:
Eric's expression is :

and Andrea's is :

In Eric's expression, 20 represents the initial amount of substance with which he has started the experiment.
is the amount of substance left after each time period (in this case, each week).The variable w in this case represents the number of weeks.
Andrea's expression can be written as :

The one outside of parentheses represents the initial amount of the substance. The one inside of parentheses represents 100% of the original amount of the substance. 0.5 represents the 50% of the substance that is lost each time period. The variable w in this case represents the number of weeks.
An equation is formed of two equal expressions. The solution is (-9,-2).
<h3>What is an equation?</h3>
An equation is formed when two equal expressions are equated together with the help of an equal sign '='.
Given the equation x + 3y = -15 and -3x + 2y = 23,
Step 1- Multiply the equations to make the coefficients match in either the x- or y-variable.
x + 3y = -15
3x + 9y = -45
Step2- After you multiply, add or subtract the two equations.
3x + 9y -3x + 2y = -45 + 23
Step 3- Then solve for the variables that is left.
11y = -22
y = -2
Step4- Substitute the value of y in any one of equations to solve for x.
x + 3(-2) = -15
x - 6 = -15
x = -9
Hence, The solution is (-9,-2).
Learn more about Equation:
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I think the interest is 10.60.
And the proceeds are 278.40.
Try to do them on math -way