2x + 4 = 2x + 2
2x - 2x = 2 - 4
0 = -2 ......(when the variables drop out and ur left with an untrue statement, this means there are no solutions)
2x + 5 = 2x + 5
2x - 2x = 5 - 5
0 = 0.....(when the variables drop out and ur left with a true statement, this means there is infinite solutions)
so the two possible solutions when the variables drop out are : no solutions and infinite solutions