Maya needs $48$ sq ft of tile for a backsplash. Basic tiles cost \$9 per sq ft and designer tiles cost \$25 per sq ft. She wants the overall average cost to be $\$14$ per sq ft. How many square feet of each tile should she use?

Mia has a jar containing nickels and dimes worth \$4.80 in total. If she has $12$ more dimes than nickels, how many of each coin does she have?

A technician needs to prepare a disinfectant by mixing a $70\%$ isopropyl alcohol solution with some $50\%$ solution to obtain $65\%$ alcohol. If the technician uses of the $50\%$ solution, how many $mL$ of the $70\%$ solution must be added?

A candy maker has $300\mathrm{mL}$ of a $45\%$ sugar syrup. She wants to dilute it with pure water to make a $30\%$ syrup. How many $mL$ of water should she add?

A retirement fund invests some money in government bonds at $2.5\%$ annual simple interest, and \(5,000 more than that amount in corporate bonds at $4\%$. If the total annual interest earned is \)1,450, how much was invested in each type of bond?

Elena has \(18,500 to invest. She invests some of it at $8.4\%$ annual simple interest for $1$ year, and the remainder at $11.6\%$ annual simple interest for $8$ months. At the end of the year, her total interest earned is \)1,500. How much did she invest at each rate?