There is only one solution in the given equation -y2 − [-5y − y(-7y − 9)] − [-y (15y + 4)] = 0. In solving this problem, apply first PEMDAS (parenthesis, exponents,multiplication, division, addition, subtraction). Then equation will transform into -y2+5y-7y2-9y+15y2+4y=0. Combine terms with same power and achieve 7y2=0. Divide both sides with 7 and perform square root of zero. Since the root is zero, we have one solution of the given equation which is y=0.
If there are 5 different shaped erasers and 8 of each, you would have to multiply which equals 40. If there are 4 people in the group, 40 divided by 10 equals 4.