ok first you can keep everything as fractions or you can turn everything to decimals I will show you both ways starting with the fraction way
to do it the fraction way the first thing you need to do is simplify 1/2y to y/2 then add 21/4 to both sides which gives you 1/2y=-7/2 then you multiply each side by 2 which now makes it y=-14/2 and when u reduce -14/2 it leaves you with y=-7