Question 1111142
{{{(ax - 4)(bx + 7) = 30x^2 + cx - 28}}}
{{{abx^2-4bx+7ax-28}}}={{{30x^2+cx-28}}}
{{{abx^2+(7a-4b)x-28=30x^2+cs-28}}}


Compare the corresponding parts to show
{{{system(ab=30,7a-4b=c)}}}


Can you continue from that?