Question

subtract two - digit numbers by adding up
study the example that shows how to subtract two - digit numbers by adding up. then solve problems 1 - 6.
example
a store has 82 hats. there are 45 blue hats. the rest are red. how many hats are red?
$82 - 45 = \boxed{?}$ is the same as $45 + \boxed{?} = 82$.
you can add tens first. then add ones.
$45 + 30 = 75$
$75 + 5 = 80$
$80 + 2 = 82$
$30 + 5 + 2 = 37$. there are 37 red hats in the store.
mr. kent needs 74 plates for a picnic. he has 28 plates. he will buy the rest of the plates he needs.
1 show how you can find how many plates mr. kent needs to buy. fill in the blanks to find $74 - 28$. add tens first.
$28 + \underline{\quad\quad} = 68$
$68 + \underline{\quad\quad} = 70$
$70 + \underline{\quad\quad} = 74$
$40 + \underline{\quad\quad} + \underline{\quad\quad} = \underline{\quad\quad}$
2 how many plates should mr. kent buy?
$\underline{\quad\quad}$ plates

Explanation:

Problem 1

Step1: Find the first blank (28 + __ = 68)

To find the number, we calculate \( 68 - 28 = 40 \). So \( 28 + 40 = 68 \).

Step2: Find the second blank (68 + __ = 70)

Calculate \( 70 - 68 = 2 \). So \( 68 + 2 = 70 \).

Step3: Find the third blank (70 + __ = 74)

Calculate \( 74 - 70 = 4 \). So \( 70 + 4 = 74 \).

Step4: Find the sum of the added numbers

We added 40, 2, and 4. So \( 40 + 2 + 4 = 46 \).

To find how many plates Mr. Kent should buy, we calculate \( 74 - 28 \). From the previous steps, we know that when we add up to find the difference (by adding to 28 until we reach 74), the total added is 46. So \( 74 - 28 = 46 \).

Answer:

First blank: 40; Second blank: 2; Third blank: 4; Sum: 40 + 2 + 4 = 46

Problem 2