This document appears to be an answer key for a math practice exam for a 3rd period class at Colegio San Patricio for the 2009-2010 school year. It provides answers to binary conversion problems, number line problems, true/false problems evaluating mathematical statements, word problems involving algebra, and expressions involving simplification and writing in algebraic form. The document concisely summarizes the essential information and key for a math practice exam.

1. COLEGIO SAN PATRICIO
ANSWER KEY
Math Practice for 3rd Period Exam
School Year 2009 – 2010
Binary System
48 = 110000 104 = 1101000
58 = 111010 202 = 11001010

2. The Number Line
Write the missing numbers.
Order the next numbers in the number line.
0, , 0.50 , , 1 , 1.25 , 2
Answer the next problems.
Is it correct?
1. 2x + 6 = 12 CORRECT Two times a number, plus six is
twelve.
2. (5) (6) − x = 25 INCORRECT Five times the difference of six
5(6−x)=25 and a number is twenty five.
3. 8(4 + 9) = 104 CORRECT Eight times the sum of four and
nine is one hundred four.
Solve.
1. If 2/3 of the pizza is left, what part will you and your two friends get?
A: for each. (You divide 2/3 by the 3 friends)
2. My brother will be forty years old in forty years. Let b be the age of my
brother now:
A: b) b+4 = 40

3. 3. Donna got 84 in a quiz, which includes 5-point bonus. Let x be the
grade she would have had without the bonus.
A: c) x + 5 = 84
4. I have to check 90 exams. I have checked 35. How many exams am I
missing?
A: Possible equation: 90 −35 = x I am missing 55 exams
55 = x
5. One trip is ¾ kms. If we decide to take 6 trips, how many kilometers
are we going to travel?
A: 4 ½ kms. (You multiply ¾ by the 6 trips)
6. You are shopping for earrings. The sales tax is 5%. You have a total of
$18.37. What is your price limit for the earrings?
A: The price limit is $17.49. Solution:

4. Simplify the expressions.
1. −6(a+8) −6a−48 3. 4(1+9x) 4+36x
2. 6(−5n+7) −30n+42
Write each as an algebraic expression.
1. The difference of 10 and 5 10−5
2. The quotient of 14 and 7 14÷7
3. u decreased by 17 u − 17
4. The product of x and 7 7x
5. Twice q 2q