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 is C

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\(\frac{3}{4}\)