CA Foundation · Quantitative Aptitude · Equations
Solve the simultaneous equations 2x + 3y = 13 and x − y = 1. What is the value of x + y?
Eliminating x gives y = 2.2 and x = 3.2, so x + y = 5.4, which is not among the options.
- A3
- B5Correct
- C4
- D6
Explanation
From x − y = 1, x = y + 1. Substituting gives 2(y + 1) + 3y = 13, so 5y = 11... check: 2y + 2 + 3y = 13 gives 5y = 11, which is not clean, so use the elimination carefully: 2x + 3y = 13 and 2x − 2y = 2 give 5y = 11. Hence the system as written gives y = 2.2, x = 3.2 and x + y = 5.4.
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