Question 252805
the point of intersection is the solution of the two equations.
It is where the two equations cross and have the same x and y
You solve the equations by elimination or substitution.
In this case it is begging for substitution because one of the equations is already  solved for y in terms of x
y=3x+1
so substitute 3x+1 in the other equation for y and solve that equation for y
x+3y=6
x+3*(3x+1)=6
x+9x+3=6
10x=3
x=3/10
y=3x+1
y=3(3/10)+1
y=9/10+1
y=1.9
x=.3=3/10
check
x+3y=6
.3+3*1.9=6
.3+5.7=6
6=6
ok
y=3x+1
1.9=3*.3+1
1.9=.9+1
1.9=1.9
ok
*[invoke linear "x", "y", 1, 3, 6, 3, -1, -1 ]