There are 4 significant figures as the zero is placed between significant numbers.
A + 2c - 5b - c + a - b
We're gonna have to combine like terms.
(a+a)+(-5b-b)+(2c-c)
2a-6b+c This is your answer
Its the square root of 1.5*20 which is root 30
A
Because 136 trading cards
15 goes to each 3 friends
The midpoint here which is = to M is (8, 1). Hope this helps