Subtracting a number is the same as adding its opposite.

Example: -13 – 7 = -13 + (- 7) = -20

Example: 17- 8 = 17 + (-8) = 12

Example: -13 – (- 7) = -13 + 7 = -6

Example: 17 – (-8) = 17 + 8 = 25

Example: 67 – (- 45) = 67 + 45 = 112

Example: -17 – (-30) = -17 + 8 = -13



Mavis Marble uses her new Mitra Card (
the card that does the math for you ) to buy material and yarn. She has been using it for 4 months. She just got a letter in the mail saying her account is now at -355.

"This can't be. My card says I have a credit of $240."

Mavis will need to compare her Mitra card charges with her payments.

Find the correct balance for her Mitra account.

 

 Mitra Charges  Payments  Balance
 -80 sewing material  -(-60)  60
 -120 sewing material  -(-60) 120
 -60 sewing material  -(-60)  180
 -95 sewing material  -(-60)  240

Find the difference and input the correct balance.  

Alpha | Go on to the Interactive Activity at the Red Box Division

 

 writer: Kevin Gallagher/mC