Question

Solve using substitution. х + бу = 20 -6x — 8y = 20 (_ , _)

Answer 1

Given the following system of equations:

`\begin{gathered} x+6y=20 \\ -6x-8y=20 \end{gathered}`

to solve by substitution, first notice that we can solve for x on the first equation to get the following:

`x=20-6y`

substituting this value on the second equation we get:

`\begin{gathered} -6(20-6y)-8y=20 \\ \Rightarrow-120+36y-8y=20 \\ \Rightarrow36y-8y=20+120 \\ \Rightarrow28y=140 \\ \Rightarrow y=(140)/(28)=5 \\ y=5 \end{gathered}`

now that we have that y=5, we can find the value of x by using our first equation:

`\begin{gathered} x=20-6(5)=20-30=-10 \\ x=-10 \end{gathered}`

therefore, the solution is (-10,5)