various problems on fraction and improper number

Please see attached file for full problem description.

Problems #'s 18, 38, 44, 50 these I need help completing

Add. Write all answers in lowest terms.
18. 13/18 + 11/18

Evaluate each of the following. Write all answers in lowest terms.
38. 9/11 - 3/11

44. Number problem. One task took 7 minutes (min), a second task took 12 min, and a third task took 21 min. How long did the three tasks take, as a fraction of an hour?

50. Geometry. Find the perimeters of the following triangles.

Find the least common multiple (LCM) for each of the following groups of numbers. Use whichever method you wish.
22. 12, 20, and 35

Add.
36. 1/3 + 5/12 + 4/5

Subtract.
44. 13/15 - 11/20

Benjamin and Olivia are putting a new floor in their kitchen. To get the floor up to the desired height, they need to add 1 1/8 ft of subfloor. They can do this in one of two ways. They can put 1/2 -in. sheet on top of 5/8-in. board (note that the total would be 9/8 ft or 1 1/8 ft). They could also put 3/8-in. board on top of 3/4 -in. sheet. The table below gives the price for each sheet of plywood from a Home depot store on 1/15/04.

Thickness Cost for a 4 ft x 8 ft Sheet
1/8 in. $9.15
1/4 in. 13.05
3/8 in. 14.99
1/2 in. 17.88
5/8 in. 19.13
3/4 in. 21.36
7/8in. 25.23
1 in. 28.49

1. What is the combined price for a 1/2 -in. sheet and a 5/8 -in. sheet?
2. What is the combined price for a 3/8-in. sheet and a 3/4 -in. sheet?
3. What other combination of sheets of plywood yields the needed 1 1/8 -in. thickness?
4. Of the four combinations, which is most economical?
5. The kitchen is to be 12 ft x 12 ft. Find the total cost of the plywood you have suggested in question 4.

Solve the following applications.
30. Statistics. Robin ran mi on Sunday, mi on Tuesday, and mi on Friday. How far did she run during the week?

48. Business and finance. The interest rate on an auto loan in May was %. By September the rate was up to %. How many percentage points did the interest rate increase over the period?

14. Business and finance. Julio works as a quality control expert in a beverage factory. The assembly line that he monitors produces about 20,000 bottles in a 24-hour period. Julio samples about 120 bottles an hour and rejects the line if he finds more than of the sample to be defective. About how many defective bottles should Julio allow before rejecting the entire line?

16. Business and finance. Lunch meat sells for about $3 per pound. You use about pound per day for sandwiches. How much should you budget for lunch meat over the next month (about 20 workdays)?

Estimate the following products or quotients.