Question 289082

Since they both equal y, set them equal to each other and solve for x.
Then go back and solve for y.
You're solving for the intersection of a line and a parabola. 
{{{x^2-x-20=3x-15}}}
{{{x^2-4x-5=0}}}
You can factor
{{{ (x-5)(x+1)=0}}}
Two solutions:
{{{x-5=0}}}
{{{x=5}}}
Then use either y,
{{{y=3x-15=3(5)-15=15-15=0}}}
(5,0)
.
.
.
{{{x+1=0}}}
{{{x=-1}}}
{{{y=3x-15=3(-1)-15=-18}}}
(-1,-18)
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.
.
Graphically
{{{ graph( 300, 300, -8, 8, -20, 4, 3x-15, x^2-x-20) }}}