Please teach me how to do this?

At the "no mutants allowed" country farm, every sheep has 4 legs, every chicken has two legs, and all animals have only 1 head. asked to count how many sheep and chicken are in the fields, a farm boy reports back that there are 140 feet and 50 heads. how many sheep and chicken are there? there are sheep and chicken at the farm.

Find the volume of the solid obtained by rotating the region enclosed by the curves y=1x and y=7^-x about the x-axis. (use symbolic notation and fractions where needed.) volume =

Acable company claims that the average household pays $78 a month for a basic cable plan, but it could differ by as much as $20. write an absolute value inequality to determine the range of basic cable plan costs with this cable company. a. |x − 78| ≥ 20 b. |x − 20| ≥ 78 c. |x − 20| ≤ 78 d. |x − 78| ≤ 20