22/ an online computer service charges one hourly rate for regular use and a higher hourly rate for designated permium services. A customer was charged $14.00 for 9h of basic use and 2h of premuim use. another customer was charged $13.50 for 6h of regular use and 3 h of premium use . what is the service charge per hour for regular and premium services?
23/ Terra cotta art center recieves an anual income of $915 from two simple interest investments. one investment, in a corporate bond found, earns 8.5% annual simple interest. the seconed investment , in a real estate investment trust, earns 7% annual simple interest. if the total amount invested in the two account is $12000, how much is invested in each account?
25/ mosher childrens hospital received a $300,000 donation that it invested in two simple interest accounts, one earning 5.4% and the other earning 6.6%. If each account earned the same amount of annual interest. how much was invested in each account?