Third Grade Equations

What equation matches this problem:  There are 4 bins of books with 10 books in each bin.  How many books?

• 10 + 4 = b
• 10 - 4 = b
• 4 X 10 = b
• 4 + b = 10

What equation matches this problem:  There are 18 birds in a tree. 7 fly away.  How many birds are left in the tree?

• 18 - 7 = b
• 18 + 7 = b
• 7 X b = 18
• b x 2 = 18

What equation matches this problem:  Joe has 13 red cars and 5 green cars.  How many cars does he have altogether?

• 13 - c = 5
• 5 + c = 13
• c X 5 = 13
• c = 13 + 5

What equation matches this problem:  Tina has 21 dog biscuits.  She give 3 to her dog each day.  How many days with the biscuits last?

• d = 21 / 3
• d = 21 - 3
• d = 21 + d
• d = 21 X d

Solve:
 x = 3 + 7

• x = 3
• x = 7
• x = 10
• x = 21

Solve:  
15 = x + 7

• x = 7
• x = 8
• x = 9
• x = 12

Solve:  
50 = 5 * x

• x = 10
• x = 45
• x = 50
• x = 55

Solve:  
x = 35 / 7

• x = 30
• x = 5
• x = 42
• x = 28