Pick the Equation
Mr. Anderson stacked wood after selling 25 from 185. Each pile has 40 pieces.
👉 What equation finds the number of piles?
p = (185 – 25) ÷ 40
b = 429 − (39 × 9)
b = 429- 351
b = 78
What does (500 − 260) represent in Theo’s problem?
Money from hot dogs
Why is adding instead of subtracting wrong in Theo’s problem?
He spent part of the money first
Theo earned $500 total. He made $260 from nachos. The rest came from hot dogs sold at $2 each.
👉 Use RDW to find how many hot dogs he sold.
Factory hats total: 2,148,431. The first 3 weeks are known. Week 4 = n.
👉 Which equation represents this?
2,148,431 = (562,937 + 607,822 + 492,375) + n
h = (500 − 260) ÷ 2
h = 240 ÷ 2
h= 120
What does dividing by 2 mean in Theo’s problem?
Price per hot dog
Why is multiplying instead of dividing wrong for piles of wood?
We are grouping, not combining
Mrs. Colton’s bonus: b = 429 − (39 × 9)
👉 Use RDW
Family spent $93 total: $18 tickets, $36 food, rest games.
👉 Equation?
93 = g + 36 + 18
s = (50 − 44) ÷ 2
s = 6 ÷ 2
s = 3
What does (31 + 41) represent in the apple problem?
Apples in one box
Why is this wrong: 93 = 36 − 18 − g?
Order and operations don’t match situation
Mr. Fernández packed (31 red + 41 green) apples into 8 boxes
👉 Use RDW to find total apples
The fence is 144 ft. Each section = 4 ft and costs $12.
👉 Equation for total cost?
(144 ÷ 4) × 12 = b
r = [625 − (7 × 55)] ÷ 8
r = [625 - 385] ÷ 8
r = 240 ÷ 8
r = 30
What does × 8 represent?
8 boxes
Why is (12 × 4) × 144 wrong for the fence?
Mixing units; must find sections first
The fence is 144 ft. Each section is 4 ft and costs $12
👉 Use RDW to find total cost
Car rental problem (multi-step)
👉 Which equation shows cars left?
c = 45 − (5 × 3) − (3 × 2) + 17
p = 6(3) + 21(2) + 16
p = 18 + 42 + 16
p = 76
What does subtracting (5×3) and (3×2) represent in the car problem?
Cars rented each hour
Why is c = 45 − (5 + 3) − (3 + 2) − 17 wrong?
It adds hours instead of multiplying cars per hour.
Car rental problem:
Start with 45 cars