If x + 0.4y = 3 and y = (frac{1}{2})x, find the value of (x + y)
-
A.
1(frac{1}{4}) -
B.
2(frac{1}{2}) -
C.
3(frac{3}{4}) -
D.
5
Correct Answer: Option C
Explanation
x + 0.4y = 3…(i)
y = (frac{1}{2})x
x = 2y
x – 2y = 0….(ii)
solve simultaneously; x + 0.4y
= 3 – x – 2y = 0
2.4 = 3
y = (frac{3 times 10}{2.4 times 10} )
= (frac{30}{24} = frac{5}{4})
x – 2((frac{5}{4})) = 0
x – (frac{5}{2}) = 0
x = (frac{5}{2})
x + y = (frac{5}{2} + frac{5}{4})
(frac{10 + 5}{4} = frac{15}{4})
= 3(frac{3}{4})