So, the question is :

If 3 different numbers are taken from the set {0,1,3,5,7} to be used as the coefficient of a standard quadratic equation

a) How many such quadratic equations can be formed?

b) How many of these have real roots

I have work on it, but the result is different from the answer key.. So anyone please help me what I've done wrong...

This is what i've done

and I got 60+12+12 = 84 equations for (a) and 18 equations for (b)

but the book says it should be 88 for (a) and 28 for (b)