10th Grade Math
posted by Crissy XD .
Mr. Badger bought 12 pens every month until their price rose to 15 cents each. Now he can only afford to buy 10 pens at the same total cost as before. What was the original price of each pen?
There are 41 pigs and chickens on a farm. If there are 100 legs counted altogehter, how many of each animal are there?
One day, 5/6 of the office staff came to work. If three more had been away, this fraction would have decreased to 3/4. How many people are on full staff?
Mrs. Grant was 20 when her eldest child, tess, was born. Carly was born 2 years later and Troy another 4 years later. Now the average of their four ages is 39. How old are Mrs. Grant and her three children?
Please help...

1.
new price x cents
solve 10x = 12(15)
2. number of chickens  x
number of pigs  41x
solve : 2x + 4(41x) = 100
3. number of people  x
(5/6)x  3 (3/4)x
4. let the number of year since Troy was born be x
Mrs. Grant = 20+6+x
Tess = 6+x
Carly = 4+x
Troy = x
solve : 26+x + 6+x + 4+x + x = 4(39)