I can't figure out where I'm going wrong on this.....help please!

Points A(5,0), B(-1,4) a find slope first

M AB=(4-0)/(-1-5)=4/-6, so m=-2/3

y=mx+b

y=-2/3x+4

The school server says the correct answer is y=-2/3x+10/3......

I thought I knew this stuff