May 13-17

Grade 8 Problem of the Week May 13-17

Show all your work

1. Solve for the unknown and verify the result. 

a) 3n -5 = -11  

b) -5c + 8 = -12

2. Sara has $75 in her bank. She puts in $13 every week. She has a total of $140 in her bank account.

a) Write an algebraic equation to find out how many weeks she has been saving for.

b) Solve it. 

c) Verify your solution.

3. Steve buys two CDs at the music store with a $20 bill and gets $3 change.  If each CD was the same price, how much did each one cost? 

a) Write an algebraic equation. 

b) Solve it. 

c) Verify your solution.

4. For each problem explain what the student did wrong then give the correct value for the unknown.

a)  x + 5 = -7                                 b)  -3x -12 = 21

x +5 -5 = -7 - 5             -3x -12 + 12 = 21+12

x = -2                                         -3x = 33

3       3

                                                 x = 11