Unit 3 Test

solve for the variable

100

x+5=17

x=12

200

3x=27

x=9

300

4x−6=30

x=9

400

3x+12=57

x=15

500

7x−18=4x+15

x=11

word problems

100

A teacher buys 4 identical packs of markers and a $7 organizing bin.
She spends $31 total.
How much does one pack of markers cost?

4x+7=31

x=6

200

A museum charges a group fee of $12 plus $8 per student.
The total cost for the trip was $100.
How many students went?

8x+12=100

x=11

300

Sam earns $5 for each cup of lemonade he sells.
He already had $18 in his money box from last week.
Now he has $63.
How many cups did he sell today?

5x+18=63

x=9

400

A pet store packs dog treats into bags.
Each bag contains 4 identical small treat packets and one 6-ounce bone.
Each complete bag weighs 38 ounces.
How much does one small treat packet weigh?

4x+6=38

x=8

500

A store discounts every tablet by $15 and sells 7 tablets, ending with $980 in revenue.
What was the original price before the discount?

7(x−15)=980

x=155

distribute the expression

100

3(x+4)

3x+4

200

2(5+x)

10+2x

300

4(2x−3)

8x-12

400

5(x+8)−3x

5x+40-3x

2x+40

500

2(3x−7)+4(x+6)

6x-14+4x+24

10x+10

two step equations

100

3x+4=19

x=5

200

5x−7=28

x=7

300

x/3 + 5=11

x=18

400

6(x−2)=36

x=8

500

4x+12=3x+27

x=15

error analysis

100

A student solves the equation x+7=28

and writes:

x=28+7
x=35

he did not use inverse operations. 

x=21

200

A student solves 6x=42

and writes: 

x=42−6
x=36

Student subtracted instead of dividing by 6.
x=7

300

A student rewrites 4(x+3)

as 4x+3

They did not distribute correctly.

4x+12

400

A student solves 3x−12=15

as:

3x=3
x=1

Student did not use inverse operations.

x=9

500

A student solves 6x+4=2x+20

and writes:

6x+2x=20−4
8x=16
x=2

student did not use inverse operations when moving numbers from one side of the equal sign to the other.