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`