well you have to factor first factoring gives you two value that you can multiply and get you a broken down version of that
you can do it two ways using the quadratic formula to factor or if you're really good at factoring just do it mentally (2x-5)(x+1)=0
for the mental way of doing the factors just set both 2x-5 equal to zero and x+1 = to zero
2x-5=0
2x=5
x= 5/2
x+1=0
x=-1
therefore the solutions are x = 5/2,-1
but if you want to learn how to do it mentally and with the quadratic function formula
let me know