Solve and Write Addition and Subtraction Equations

You have some trading cards. You give 21 cards to a friend and have 9 left for yourself. How many cards were in your original deck?

*Submit only the number as your answer*

Which choice models this situation?
Robyn had some video games, then bought 4 more.  Now she has a total of 10 games.

• v - 4 = 10

• v + 4 = 10

• 10/4 = v

• 4v = 10

Use the strip diagram to write an equation. Then solve. Kiki had 17 mystery books. She got some more mystery books as a gift. Now she has a total of 21 mystery books. How many books did Kiki receive as a gift?

• 21 = 17 + p

• 21 + 17 = p

• 4

• 38

Use the strip diagram to write an equation. Then solve. The pet store had some goldfish. Eight goldfish were sold. There are 28 goldfish left. How many goldfish did the pet store have before some were sold?

• 36

• 28 - 8 = f

• f − 8 = 28

• 20

Solve for x. -16+ x= -15

x + 12 = 20

• x = 32

• x = -32

• x = 8

• x = -8

Solve for y:

y + 51 = -99

• y = -44

• y = 150

• y = -150

• Answer not Given

In order to solve 6j - 9 = 27, I would first ​ (a)   , then ​ (b)   .

• add 9 to both sides

• subtract 9 from both sides

• divide by 9 on both sides

• divide both sides by 6

• subtract 6 from both sides

• add 6 to both sides

Solve the equation.

x + 9 = -5

Mathematical Equivalence

OFF

x - 5 = -14