Question

How do you solve the system of equations `8x + 3y = 93` and `4x + 3y = 69`?

Answer 1

`(x,y)=(6,15)`

Explanation:

Given
[1]`color(white)("XXX")8x+3y=93`
[2]`color(white)("XXX")4x+3y=69`

after subtracting [2] from [1]
[3]`color(white)("XXX")4x=24`

then dividing both sides of [3] by `4`
[4]`color(white)("XXX")x=6`

Now substitute `6` for `x` in one of the original equations (I choose [2])
[5]`color(white)("XXX")4xx6 + 3y =69`

subtract `4xx6=24` from both sides of [5]
[6]`color(white)("XXX")3y=45`

divide both sides of [6] by `3`
[7]`color(white)("XXX")y=15`