Sangster Math, May 27

 May 27, 2022, adding and subtracting negative integers

 

14 + 12                                    14 + (–12)                                14 – (–12)                    14 – (+12)

= 26                                         = 14 – 12                                 = 14 + 12                     = 14 – 12         

                                                = 2                                           = 26                             = 2

 

 

Mr Kwok thinks about MONEY all the time, even in his sleep

 

Positive number: earning or making money

Negative number: spending money, debt

 

 

14 + 12                                                                        14 + (–12)                                

= 26                                                                             = 14 – 12                                             

                                                                                    = 2                                           

 

- I have $14 in my wallet,                                            - I have $14 in my wallet

My parents give me $12.                                            I spend $12 for lunch

Now, I have $26                                                          Now, I only have $2 in my wallet

 

 

Try these questions

 

18 + (–12) – (–7)                                 23 – (–9) + (–5)                       55 – (+17) + (–10)

= 18 –12 +7                                         = 23 +9–5                                = 55 – 17 –10

= left to right                                       = left to right                           = 38 – 10

= 6 + 7                                                 = 32 – 5                                   = 28

= 13                                                     = 27

 

 

Problem solving based algebra

 

My dad is 7 times older than me, and my sister is twice as old as me. All together, the sum of our age is 120 years. How old is my dad?

 

Step 1:  Find the person with the least/lowest/youngest. Give that person one box

 

Me 

 

Step 2: How many boxes will you give sister and dad?

 

 

 

All together, there are 10 boxes

All together, 120 years

 

How many years in one box? 120/10 = 12 years in one box

 

Dad has 7 boxes, 7 x 12 = 84 years

 

 

2a) Amir reads twice as many books as Kwok. Kate reads three times more than Kwok. All together, they read 192 books. How many books did each read?

2b) Sybil reads four times more than Bruce.  Charlie reads twice as much as Bruce.  All together, they read 56 novels last month.  How many novel did Sybil read? [ans: 32]

2b) Enriko eats three times more ice cream sandwiches than Eric. Evan easts the same amount as Enriko. All together, they eat 91 ice cream sandwiches. Determine how many did each person eat.

3b) In a race, Leah runs 8 times more distance than Biden, and Reid runs 6 times more distance than Biden. If Leah runs for 44Km, how many km did Reid and Biden run?