How much 30% acid solution should be added to 10% acid solution to make 100 ml of a 12% acid solution?

Pls an ice cream shop sells 5 times as many cake cones as waffle cones use variable x to represent the number of waffle the ice cream shop sells and use this variable to write an expression for the number of cake cones the ice cream shop sells. enter the expression for the number of cake cones the ice cream shop sells

Arestaurant offers a $12 dinner special that has 5 choices for an appetizer, 12 choices for an entrée, and 4 choices for a dessert. how many different meals are available when you select an appetizer, an entrée, and a dessert? a meal can be chosen in nothing ways. (type a whole number.)

This is a map of the mars exploration rover opportunity predicted landing site on mars. the scale is 1cm : 9.4km. what are the approximate measures of the actual length and width of the ellipse? i mostly need to know how to set it up : )