How do you solve the following system?: 3x +y =15 , -9x +8y = 4

1 Answer
Jul 30, 2016

There are many ways to solve this.I'm using substitution method.
lets see:

Explanation:

3x+y=15
impliesy=15-3x(equation 1)

putting the value of y in equation 2
-9x+8(15-3x)=4
implies-9x+120-24x=4
implies-33x=-116
impliesx=(-116)/-33
impliesx=3.51

putting the value of x in equation 1
y=15-3*3.51
impliesy=15-10.53
impliesy=4.47

therefore x=3.51 and y=4.47