Question

If 13x + 27y = 40 and 27x + 13y = 80 then x + y (A) 120 (B) 8 (C) 4 (D) 3​

Answer 1

Answer:

D)3

Step-by-step explanation:

$13x + 27y = 40 \\ 27x + 13y = 80 \\ 40x + 40y = 120 \\ x + y = 120 \div 40 \\ x + y = 3$

Answer 2

SOLUTION

TO CHOOSE THE CORRECT OPTION

If 13x + 27y = 40 and 27x + 13y = 80 then x + y

(A) 120

(B) 8

(C) 4

(D) 3

EVALUATION

Here the given equations are

13x + 27y = 40 - - - - - - (1)

27x + 13y = 80 - - - - - - (2)

Adding Equation 1 and Equation 2 we get

$\displaystyle \sf{ 13x + 27y + 27x + 13y = 40 + 80 }$

$\displaystyle \sf{ \implies 13x + 27x + 27y + 13y = 40 + 80 }$

$\displaystyle \sf{ \implies 40x + 40y = 120 }$

$\displaystyle \sf{ \implies 40(x + y) = 120 }$

$\displaystyle \sf{ \implies (x + y) = 3 }$

FINAL ANSWER

Hence the correct option is (D) 3

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