Question

Solve the system by using substitution

4y = x
3x - y = 70

A) (2 2/3, 1 1/3)

B) (25 5/11, 6 4/11)

C) (35, 8 3/4)

D) (6 4/11, 25 5/11)

Please help and explain!!

Answer 1

put x=4y in 3x-y=70

3(4y)-y=70

12y-y =70
11y=70
therefore y =70/11

x=4y
therefore
x=4(70/11)
x=280/11

Answer 2

Solution......

x = 4y ............eq.(1)

3x - y = 70........... eq.(2.)

put x = 4y in eq.2
we have,

12y - y = 70

11y = 70

y = 70 / 11

put value of y in eq.1

x =( 4 × 70) / 11

x = 280/11.