Question

Solve each system using substitution. 3x+2y=23 1/2x-4=y

Answer 1

$\left\{\begin{array}{ccc}3x+2y=23&(1)\\y=\frac{1}{2}x-4&(2)\end{array}\right\\\\subtitute\ (2)\ to\ (1)\\\\3x+2(\frac{1}{2}x-4)=23\\3x+x-8=23\\4x-8=23\ \ \ \ |add\ 8\ to\ both\ sides\\4x=31\ \ \ \ \ |divide\ both\ sides\ by\ 4\\\boxed{x=7.75}\\\\subtitute\ the\ value\ of\ "x"\ to\ (2)\\\\y=\frac{1}{2}(7.75)-4\\y=3.875-4\\\boxed{y=-0.125}\\\\Answer:\boxed{ \left\[\begin{array}{ccc}x=7.75\ (7\frac{3}{4})\\\\y=-0.125\ (-\frac{1}{8})\end{array}\right}$

Answer 2

1: 3x+2y=23
2: 1/2x-4=y
We have that y=1/2x-4 in 2
So lets substitu y in 1
3x+2(1/2x-4)=23
3x+x-8=23
4x=23+8
4x=31
X = 7,75
Now lets replace x in 2:
1/2.7,75-4=y
3,875-4 + y
Y= - 0,125
So (x;y)=(7,75;-0.125)