SUBTRACTING INTEGERS

7th Pre-Algebra

WARM UP1. A person blinks an average of 25 times

per minute when awake. Last year (not a leap year), Katelyn averaged 9 hours, 45 minutes of sleep each day. How many times did Katelyn blink last year?

CHECK HW

SUBTRACTING INTEGERSUsing number chips:A. 5 – 3 = B. -5 – (-3) =C. -10 – (-5) =D. 5 – (-3) =E. 7 – (-4) =F. 4 – 9 =

SUBTRACTING CONTINUED:Using the number line:

A. 5 – 3 = B. -5 – (-3) =C. -10 – (-5) =D. 5 – (-3) =E. 7 – (-4) =F. 4 – 9 =

0 1 2 3 4 5 6 7 8 9 10 11 12 130–1–2–3–4–5–6–7–8–9–10–11–12–13

REAL WORLD EXAMPLEThe Spartan Bike Shop keeps a record of

their business transactions. They start their account a zero dollars. Payments represent negative transactions. Sales represent positive transactions. Write a number sentence to represent each transaction. Then find the new balance.

SPARTAN BIKE SHOP Rent payment for shop: $1,800 Payment for 20 new bicycles: $2,150 Payment on office equipment: $675 Business insurance for 6 months: $2,300 Sale of 3 bicycles: $665 Sale of two helmets and one baby seat: $95 Web site advertising down payment: $250 Sale of 6 bicycles: $1,150 Refund to an unhappy customer: $225 Sale of 2 bicycles, two helmets, and two air

pumps: $750 Check from manufacturer for 5 bicycles returned:

$530

HW Textbook p. 66 (9-16)