A group of students is organizing a bake sale to raise money for their school trip. They plan to sell two types of cookies, chocolate chip cookies, and oatmeal cookies. The number of chocolate chip cookies they plan to bake is represented by the variable ‘c’, and the number of oatmeal cookies is represented by the variable ‘o’.
The total cost to bake ‘c’ chocolate chip cookies is given by the expression 0.75c, and the total cost to bake ‘o’ oatmeal cookies is given by the expression 0.50o.
If the students plan to bake a total of 100 cookies, write an algebraic expression to represent the total cost of baking all the cookies. Also, determine the total cost if they bake 30 chocolate chip cookies and 70 oatmeal cookies.