An extremely large ski resort is looking into purchasing two types of ski lifts, a densely-seated one and a loosely-seated one. The densely-seated ski lift is able to bring 45 guests up the slopes every minute whereas the loosely-seated ski lift can transport 20 guests every minute.  The densely-seated ski lift uses 30 units of electricity and the loosely-seated lift uses 22 units of electricity. There must be at least five loosely-seated ski lifts because they move slower and are friendlier for beginners. The ski resort needs at least 1000 guests every minute to make a profit and has available 940 units of electricity. How many of each type of ski lifts should they plan to install to minimize the total number of ski lifts needed?