1. A lab technician needs to create 150 mL of a 20% saline solution by mixing a 10% solution and a 30% solution. How many milliliters (mL) of the 10% solution are needed? ___ mL
2. A chemist has 100 mL of an 80% acid solution. How many milliliters of a 30% acid solution must be added to obtain a final mixture that is 50% acid? ___ mL
3. To make 200 liters of a 40% fruit juice drink, a bottler mixes a 25% juice solution and a 50% juice solution. How many liters of the 50% juice solution are needed? ___ liters
4. Micah has 74 feet of fencing for a dog run. He wants the length to be 2.5 feet more than the width. Find the length, $L$, by solving the equation $2L + 2(L - 2.5) = 74$. $L = \text{\_\_\_}$ feet
5. Solve for $s$: $5 + 6(3s - 5) = -3 + 2(8s - 1)$. The value of $s$ is ___.
6. Solve for $k$: $-6 + 6(5 - k) = 15$. $k = $ ___.
7. Solve for $c$: $4[5 - 8(c - 3)] = 12(1 - 13c) - 8$. The value of $c$ is ___.