Absolute or modulus always gives a positive number.
For example, when I take absolute value of 4, I get
|4| = 4 and when I take absolute value of -4, I get |-4| = -(-4) = 4.
Therefore, no matter what the sign of quantity is, absolute or modulus will always make it positive.
Therefore,
|10 blocks| + |3 blocks| + |-8 blocks| + |2 blocks| + |-7 blocks| + |4 blocks| + |-4 blocks| = 10 + 3 -(-8) + 2 -(-7) + 4 -(-4) = 10+3+8+2+7+4+4 = 38
