Add Do Not Use a Number Line Except as a Check

question 146

Multiple Choice

Add. Do not use a number line except as a check.
- $$- \frac { 1 } { 14 } + \frac { 8 } { 21 }$$

• A) \(\frac { 11 } { 21 }\)
• B) \(\frac { 1 } { 3 }\)
• C) \(\frac { 13 } { 42 }\)
• D) \(\frac { 13 } { 21 }\)

---

Definitions:

Method of Difference

A scientific research method used to identify the cause-effect relationship between variables by changing one variable at a time while keeping others constant.

Causal Factor

An element or condition that brings about or contributes to producing a particular outcome or effect.

Method of Concomitant Variations

A principle in scientific and philosophic reasoning that suggests a causal relationship between two variables if they vary together consistently.

Method of Concomitant Variations

A scientific method where one observes the changes in one variable alongside the changes in another, determining correlation.