from the question we are required to solve for the value of e. to solve for e is very simple but always take note of the positive and negative sign for accuracy in your result.
9e-7=7e-11
collect the like terms
9e- 7 - 7e = -11
9e - 7e = -11 + 7
2e = -4
divide both sides by the coefficient of e which is 2
2e/2 = -4/2
e = -2
to check if your answer is correct put the value of e into the question and see if your right hand side equals your left hand side
