The answer would be 0
Reminder: when you see “-(-“ always think of plus sign “+.” (My teacher in middle school taught me that). So, -3+3 would be that the answer is 0.
Answer:
the commutative property of addition :)
139 + 30d = 13 + 51d
139 - 13 = 51d - 30d
126 = 21d
126/21 = d
6 = d
now lets check..
139 + 30d = 139 + 30(6) = 319
13 + 51d = 13 + 51(6) = 319
so on day 6, they will both cost $ 319
