**1. N stands for the number of hours Dennis spends on Facebook each day. Which of the following represents the number of hours Dennis spends on Facebook every week?**

**a. N + 7 b. N – 7 c. N × 7 d. N ÷ 7**[Grade 4]

2. If the number of Facebook members in a school is

*F*and the number of Twitter members*T*, and there are 40 times as many Facebookers as Twitterers, write an algebraic equation that shows this relationship. [Grade 8]**3. For next year’s Singapore App Annual Show (SAAS), a child pays $**

**x****per ticket and an adult pays $**

**y****more than a child per ticket. If**

**p****children and**

**q****adults buy tickets, find the total revenue from the sale of tickets in terms of the variables.**[Grade 8]

4. Sam has twice as many Twitter followers as Ruth. If Ruth has

*r*followers and Sam*s*followers, and Sam helps Ruth to gain a dozen followers within a week, how many followers does each have in terms of*r*? [Grade 7]**5. In the following, write an expression in terms of the given variable that represents the indicated quantity.**

**(a) The cost of having an IT repairman spend**

**t****hours at your house if he charges $40 for coming to the house and $50 per hour for labor**

**(b) The time (in minutes) left to use the mobile phone with a battery life of 8 hours, after**

**t****minutes of SMS-es and**

**k****hours writing e-mails**

**(c) The resale price of a laptop after**

**t****years if its initial price is $**

**P****and the resale value of the laptop halves every year**

**(d) Arthur’s total earnings as an ICT tutor after three years if the first year he earned $**

**x****, the second year it was $8,000 higher, and the third year it was twice as much as the second year**[Grade 8]

6. Last month, Jack, a hardcore ex-convict,

· illegally downloaded

*a*pirated blue movies;
· secretly watched

*b*YouTube adult-themed clips;
· sneeringly “defriended”

*c*Facebook members;
· insincerely clicked “Like”

*d*times;
· angrily unfollowed

*e*followers on Twitter;
· anonymously left

*f*mean comments on blog posts; and
· vengefully spammed

*g*e-mails to his ex-math teachers.
How many on-line transgressions did he commit in the last month? [Grade 7]

**7. Tom recently set up a Facebook account for his dog.**

**Freakie****has now more friends than his owner:**

**x****canine friends and**

**y****feline friends. Tom has**

**z****friends. Which of the following is true?**

**a.**

**x****+**

**y****<**

**z****b.**

**x****–**

**y****>**

**z****c.**

**x****+**

**y****>**

**z****d.**

**z****>**

**x****+**

*[Grade 7]*

**y**
8. @cobrakill tweeted the following to @MathPlus and @Zero_Math:

Scared off 3 bullies; had

*x*mice &*y*ostrich eggs for breakfast. Gobbled up a piglet & a wild cat for lunch. And terrified a trio of oldies!
How many fell prey to the king cobra? [Grade 7]

**Selected Answers**

1. c

*2. F*= 40

*T*

*3. px*+*q*(*x*+*y*) = (*p*+*q*)*x*+*qy*dollars

*4. s*= 2*r*; Sam has (2*r*– 12) followers, and Ruth has (*r*+ 12) followers.*5. (a) 40 + 50*

*t*dollars (b) 480 –*t*– 60*k*(c)*P*/2*(d) 4*^{t}*x*+ 24,000 dollars*6.*

*a*+*b*+*c*+*d*+*e*+*f*+*g**7. c*

© Yan Kow Cheong, February 8, 2012.