Question

What is the solution to this system? 3x+2y=45 4x+-y=5

Answer 1

(I) $3x + 2y = 45$

(II) $4x - y = 5$

Get $y$ alone in equation (II)

$4x - y = 5\\y = 4x - 5$

Insert new equation (II) in equation (I)

$3x + 2(4x - 5) = 45\\3x + 8x - 10 = 45\\3x + 8x = 45 + 10\\11x = 55\\x = 5$

Insert $x = 5$ in equation (II)

$y = 4 \cdot 5 - 5\\y = 20 - 5\\y = 15$