Question

PLEASE ANSWER ASAP! MUST BE CORRECT! MORE POINTS GIVEN!!!

Sally said that when you add or subtract positive or negative decimals, you can change the order of the decimals and still get the same answer.
Use these decimals to answer the questions:
–6.2, 5.71, –3.96, 2.84

Write a rule about changing the order of the numbers in adding and in subtracting positive and negative decimals.

Answer 1

These are the two rules for when a and b are positive numbers.
a + b = b + a
a - b ≠ b -a
a - b = -b + a

For example:

5.71 + 2.84 = 2.84 + 5.71
8.55 = 8.55

5.71 - 2.84 ≠ 2.84 - 5.71
2.87 ≠ -2.87

5.71 - 2.84 = -2.84 + 5.71
2.87 = 2.87



These are the rules for when a and b are negative numbers.
a + b = b + a
a - b = b + a

For example,

-6.2 + (-3.96) = -3.96 + (-6.2)
-6.2 - 3.96 = -3.96 - 6.2
-10.16 = -10.16

-6.2 - (3.96) = -3.96 + (-6.2)
-10.16 = -10.16



Also, if a is a positive number, while b is a negative number, we see these rules:
a + b = a - b
a - b = a + b

For example,

5.71 + (-6.2) = 5.71 - 6.2
-0.49 = -0.49

5.71 - (-6.2) = 5.71 + 6.2
11.91 = 11.91


Also, if a is a negative number while b is a positive number, then these rules will apply:
a + b = b - a
a - b = -b - a

For example,

-3.96 + 2.84 = 2.84 - 3.96
-1.12 = -1.12

-3.96 - 2.84 = -2.84 - 3.96
-6.8 = -6.8


I hope this helps! :)