[tex]1.\\ a)\ y=2x-3\ \ \ |subtract\ y\ from\ both\ sides\\\\\boxed{2x-y-3=0}\\\\b)\ y=\dfrac{1}{3}x-\dfrac{2}{5}\ \ \ |multiply\ both\ sides\ by\ 15\\\\15y=5x-3\cdot2\ \ \ |subtract\ 15y\ from\ both\ sides\\\\\boxed{5x-15y-6=0}[/tex]
[tex]2.\\a)\ 5x-y+3=0\ \ \ |add\ y\ to\ both\ sides\\\\\boxed{y=5x+3}\\\\d)\ 7x+2y-3=0\ \ \ |subtract\ 7x\ from\ both\ sides\\\\2y-3=-7x\ \ \ |add\ 3\ to\ both\ sides\\\\2y=-7x+3\ \ \ \ |divide\ both\ sides\ by\ 2\\\\\boxed{y=-3.5x+1.5}[/tex]
[tex]3.\\y=25x+100\ \ \ \ |subtract\ y\ from\ both\ sides\\\\\boxed{25x-y+100=0}[/tex]