John R. answered • 05/07/13

Physics and Math Tutor – Kind, Easy-going, Patient

Let x equal the number of hours at the pharmacy and y equal the number of hours babysitting. Then

15x +10y = 90

Now the last part of your question did not show up above but I am assuming that the total hours where specified, let call that T. So the second equation is:

x + y = T

Then these equations can be solved by substitution or any other preferred method of solving simultaneous equations.