Operations
How do you undo addition?
Subtraction
8x - 18 = 38
x = 7
4(2v - 9) = -12
v = 3
Sarah bought a binder for $7.25 and six folders. She spent a total of $9.05. How much did each folder cost?
let x = # of folders
7.25 + 6x = 9.05
x = 0.3
$0.30
Word problem solutions always include what?
A label
How do you undo multiplication?
Division
16 = -5m + 11
m = -1
31 = n - 3(n - 7)
n = -5
At your local farmers’ market, it costs $15 to rent a stand, and $6 for every hour you stay there. If you paid a total of $33, how many hours did you stay?
let x=# of hours
15 + 6x = 33
x= 3
3 hours
-3(6x + 2) = -42
What is the first step in solving this equation?
Distribute -3 to 6x and 2
How do you undo subtraction?
Addition
19 - 2k = -13
k = 16
-20 = -4x - 6x
x = 2
Evan used half of his paycheck for his car payment, then $125 for groceries. If he has $215 left, how much was his paycheck?
let x=paycheck
(1/2)x - 125 = 215
x=680
$680
Dividing by a fraction is the same as what?
Multiplying by its reciprocal.
(Keep Change Flip)
How do you undo division?
Multiplication
-7 - p = -5
p = -2
12 = -4(-6y - 3)
y = 0
Evan bought a bag of Skittles, ate 13 of them, then distributed the rest evenly into 4 bowls. If there are 64 Skittles in each bowl, how many were originally in the bag?
let x=Skittles at start
(x-13)/4 = 64
x=269
269 Skittles
The sum of negative three and a number, divided by seven, is negative two.
(-3 + x) / 7 = -2
x = -11What is the order of operations?
Parentheses, Exponents, Multiplication, Division, Addition, Subtraction
Ten more than half a number is fifteen.
(1/2)x + 10 = 15
x = 10
2(4v - 3) - 8 - 2v = 4
v = 3
Mara bought a bag that contained 16 cups of sugar. She uses two-thirds cup of sugar each time she makes a batch of cookies. If the bag now has 10 cups of sugar left, how many batches of cookies has she made?
let x = # of batches of cookies
16 - (2/3)x = 10
x = 9
9 batches
What three things do you need to include in your answer for word problems ?
Defined variable
Equation
Solution