- A
- B
- C
- D
Step-by-Step Solution
Substitute into each: ✓, ✓, and ✓. But , not 8, so that one fails — its solution is . Checking by substitution is far quicker here than solving all four equations.
Answer: C)
Three of these equations are satisfied by . Which one is NOT?
Class 7Simple EquationsSimple Equations
Key idea: Translating word problems into equations
Three steps:
1. **Pick a variable** for the unknown ('let be the number of …').
2. **Translate the words into an equation** using the operations the problem describes.
3. **Solve and answer in the original units.**
Example: 'Three times a number plus 7 equals 22. Find the number.'
Let = the number. Equation: . Solve: .
Answer: the number is 5.
1. **Pick a variable** for the unknown ('let be the number of …').
2. **Translate the words into an equation** using the operations the problem describes.
3. **Solve and answer in the original units.**
Example: 'Three times a number plus 7 equals 22. Find the number.'
Let = the number. Equation: . Solve: .
Answer: the number is 5.
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