[tex]\text{The slope-intercept form:}\ y=mx+b\\\\\text{m-a slope; b-a y-intercept}[/tex]
[tex]\text{We have:}\\m=5\\\text{therefore}\ y=5x+b[/tex]
[tex]\text{We know, the line passes through the point}\ (-2;\ 8)\to x=-2;\ y=8\\\\\text{substitute the values of x and y to the equation of the line:}\\\\8=5(-2)+b\\\\8=-10+b\ \ \ |+10\\\\b=18[/tex]
[tex]\text{Your answer:}\ y=5x+18[/tex]