Lesson 9
Representing Subtraction
Let's subtract signed numbers.
Problem 1
Write each subtraction equation as an addition equation.
 \(a9 = 6\)
 \(p20=\text30\)
 \(z(\text12)=15\)
 \(x(\text7)=\text10\)
Problem 2
Find each difference. If you get stuck, consider drawing a number line diagram.

\(9  4\)

\(4  9\)

\(9  (\text4)\)

\(\text9  (\text4)\)

\(\text9  4\)

\(4  (\text9)\)

\(\text4  (\text9)\)

\(\text4  9\)
Problem 3
Find the solution to each equation mentally.
 \(30+a=40\)
 \(500+b=200\)
 \(\text1+c=\text2\)
 \(d+3,\!567=0\)
Problem 4
A restaurant bill is $59 and you pay $72. What percentage gratuity did you pay?
Problem 5
One kilogram is 2.2 pounds. Complete the tables. What is the interpretation of the constant of proportionality in each case?
pounds  kilograms 

2.2  1 
11  
5.5  
1 
______ kilogram per pound
kilograms  pounds 

1  2.2 
7  
30  
0.5 
______ pounds per kilogram