Question

4 there are 86 cars in the parking lot. then 37 cars drive away. how many cars are in the parking lot now? find $86 - 37$.
a 59
b 56
c 49
d 43
5 which of the strategies below could help you find $72 - 25$? select all the correct answers.
a $72 - 30 = 42$ and $42 - 5 = 37$
b $25 + 5 = 30$ and $30 + 40 = 70$ and $70 + 2 = 72$
c
d $\

$$\begin{array}{r}6\\text{ tens }\\ 12\\text{ ones}\\\\ - 2\\text{ tens }\\ 5\\text{ ones}\\\\ \\hline\\end{array}$$

$
e $72 - 50 = 22$ and $22 - 5 = 17$

Explanation:

Step1: Calculate 86 - 37

$86 - 37 = 49$

Step2: Verify strategy A for 72-25

$72-30=42$, $42+5=47$ (incorrect, subtracts extra 5)

Step3: Verify strategy B for 72-25

$25+5+40+2=72$, so $72-25=47$ (correct)

Step4: Verify strategy C for 72-25

Number line: $72-2-5-40=25$, so $72-25=47$ (correct)

Step5: Verify strategy D for 72-25

$6$ tens $12$ ones $=72$, $2$ tens $5$ ones $=25$; $6-2=4$ tens, $12-5=7$ ones, $47$ (correct)

Step6: Verify strategy E for 72-25

$72-50=22$, $22+25=47$ (incorrect, wrong operation)

Answer:

1. C. 49
2. B. $25 + 5 = 30$ and $30 + 40 = 70$ and $70 + 2 = 72$, C. [Number line strategy], D.

$$\begin{align*} 6 \text{ tens } 12 \text{ ones} \\ - 2 \text{ tens } 5 \text{ ones} \end{align*}$$