Adding / subtracting negatives and positives

Question

Find each sum or difference and explain your reasoning:

a. +11 - +23

b. +7+-3

c. -20 + -7

d. -13 - -18

Answer 1

a 11 - (+23) = 11-23 = -(-11+23) = -(23-11) = -12

b 7+ -3 = 7-3 = 4

c -20 + -7 = -20-7 = -(20+7) = -27

d -13 - - 18 = -13+18 = 18-13 = 5

double negative is the same as a positive - - 18 = +18

adding a negative is the same as subtraction 7 + -3 = 7-3