[tex]\dfrac{2}{5}(x-4)=2x\ \ \ \ |multiply\ both\ sides\ by\ 5\\\\2(x-4)=10x\ \ \ \ |use\ distributive\ property:a(b-c)=ab-ac\\\\2x-8=10x\ \ \ |add\ 8\ to\ both\ sides\\\\2x=10x+8\ \ \ \ |subtract\ 10x\ from\ both\ sides\\\\-8x=8\ \ \ \ |divide\ both\ sides\ by\ (-8)\\\\\boxed{x=-1}[/tex]
