Question

how would i know if i need to subtract or add with questions like -50\frac{1}{2}+-12.3

Answer 1

Quick rule to decide whether to add or subtract when negatives are involved:

- If the signs are the same (both + or both −), add the absolute values and keep that sign.
- If the signs are different, subtract the smaller absolute value from the larger absolute value and keep the sign of the number with the larger absolute value.
- Also remember: subtracting a negative is the same as adding a positive (a − (−b) = a + b).

Apply to your example: -50 1/2 + -12.3

1. Convert the mixed number to a decimal: -50 1/2 = -50.5.
2. Both numbers are negative, so add their absolute values: 50.5 + 12.3 = 62.8.
3. Keep the negative sign: result = -62.8.

So -50 1/2 + -12.3 = -62.8.