Adjusting/True Equations
Antonio wants to solve 44 - 18. He adjusted the numbers. Now his problem is 46 - 20. Did he adjust his numbers correctly?
Yes, Antonio added "2" to both numbers. He correctly adjusted his numbers.
13 - 8 = ?
What are 2 related addition sentences? Solve.
*Think Commutative Property
13 - 8 = ?
? + 8 = 13
8 + ? = 13
? = 5
Decompose by place value to subtract.
75 - 14 = ?
75 - 10 = 65
65 - 4 = 61
75 - 14 = 61
80 - 39 = ?
41
Our class checked out 47 books from the library last week. This week only 28 books were returned. How many books are overdue?
47 - 28 = ?
? = 19
Adjust the numbers to find the difference of 72 - 28.
72 - 28 = ?
74 - 30 = ?
44 = ?
34 - 15 = ?
Rewrite this as an addition problem and solve.
? + 15 = 34
? = 19
17 - 9 = ?
Make a ten to subtract.
17 is 7 away from 10.
I can decompose 9 by adding 7 + 2 together.
17 - 7 = 10
10 - 2 = 8
17 - 9 = 8
53 - 18 = ?
35
Uriah and Ian's families went out to Burger King. Uriah's family's order cost $28 and Ian's family's order cost $41. Whose order cost less? How much less was it?
Uriah's family's order was less.
41 - 28 = ?
It was $13 less.
What is the unknown number?
39 - 12 = 45 - ?
39 - 12 = 27
45 - ? = 27
27 + ? = 45
? = 18
65 - 22 = ?
? + 22 = 65
OR
22 + ? = 65
56 - 24 = ?
Decompose by place value to subtract.
24 = 20 + 4
56 - 20 = 36
36 - 4 = 32
? = 32
51 - 28 = ?
23
Kodie picked out 2 dresses for the winter concert. The white dress was $38 and the green dress was $13 cheaper. What was the price of the green dress?
38 - 13 = ?
? = 25
$25
Is the equation true or false? Explain.
44 - 12 = 56 - 24
True. 44 - 12 = 32 and 56 - 24 = 32. Both sides are equal.
54 - 28 = ?
Write 2 related addition sentences. Solve.
*Think Commutative Property
? + 28 = 54
28 + ? = 54
? = 26
15 - 8 = ?
Make a 10 to solve.
This means I will decompose 8 into 5 and ?.
5 + 3 = 8.
15 - 5 = 10
10 - 3 = 7
15 - 8 = 7
Use an open number line to help you subtract.
64 - 37 = ?
64 - 37 = ?
27
Amelia flips a coin 20 times. 11 of the times it landed on heads. How many times did it land on tails?
20 - 11 = ?
? + 11 = 20
? = 9
Which ways shows how to adjust the numbers to subtract? 62 - 29 = ?
a. 60 - 27 b. 61 - 30 c. 63 - 30 d. 60 - 31
a. 60 - 27
c. 63 - 30
68 - 24 = ?
Which is a related fact?
a. ? - 24 = 68 b. 24 - ? = 68
c. ? + 24 = 68
c. ? + 24 = 68
73 - 19 = ?
Which pair of numbers correctly decomposes 19 to help you solve?
a. 1 + 9 b. 10 - 9 c. 10 + 9 d. 10 + 19
c. 10 + 9
67 - 39 = ?
Draw base-ten blocks to help you solve.
28
Haddie is putting away her Legos. She put away 34 Legos in a bin, but there are still 18 pieces on her carpet. How many Lego pieces were out at the start?
? - 34 = 18
18 + 34 = ?
52 = ?