If '+' means 'division', '-' means 'plus', 'x' means 'subtraction' and '÷'…
2017
If '+' means 'division', '-' means 'plus', 'x' means 'subtraction' and '÷' means 'multiplication', then what is the value of 13 - 4 ÷ 5 x 63 + 9 = ?
Answer: C. 26 — ConceptIn a symbol-substitution problem, first replace every given operator with the operation it stands for, rewriting the whole expression. Then evaluate…
- A.
38
- B.
25
- C.
26
- D.
22
Attempted by 6 students.
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Correct answer: C
Concept
In a symbol-substitution problem, first replace every given operator with the operation it stands for, rewriting the whole expression. Then evaluate the rewritten expression using the normal order of operations (BODMAS): do multiplication and division before addition and subtraction, working left to right within each group.
Application
Substitutions given: '+' → division, '-' → addition, 'x' → subtraction, '÷' → multiplication. Apply them to 13 - 4 ÷ 5 x 63 + 9:
Replace '-' with + : 13 - 4 becomes 13 + 4.
Replace '÷' with × : 4 ÷ 5 becomes 4 × 5.
Replace 'x' with − : 5 x 63 becomes 5 − 63.
Replace '+' with ÷ : 63 + 9 becomes 63 ÷ 9.
Rewritten expression: 13 + 4 × 5 − 63 ÷ 9.
Apply BODMAS — multiply and divide first: 4 × 5 = 20 and 63 ÷ 9 = 7.
Now add and subtract left to right: 13 + 20 − 7 = 33 − 7 = 26.
Cross-check
Re-evaluating independently: 13 + 20 = 33, and 33 − 7 = 26. The order-of-operations result is consistent, so the value of the expression is 26.