During a sleepover, Carissa played karaoke with her friends. Her song was 6 minutes long. She had already sung for 4 minutes. Which equation could be used to see how much longer she will have to sing?

x + 2 = 6
x + 4 = 10
x + 4 = 6
x − 4 = 6

Brett has a box of colored pencils. He uses 78 pencils and has 120 pencils left in the box. Write an equation showing how many pencils are in the box before he starts drawing.

78 + p = 120
p − 78 = 120
120 + p = 78
p = 120 − 78