What are all the fractions that are equivalent to 1/7

The formula for the lateral area of a right cone is la = rs, where r is the radius of the base and s is the slant height of the cone. which are equivalent equations?

Each person in an it department of 25 people works on at least one of 3 major projects: system security, program implementation, platform development. 10 people work on system security, 13 work on program implementation, and 12 work on platform development. 4 people work on system security and platform development, 5 people work on program implementation and platform development, and 2 people work on all three projects. how many people work on system security and program implementation?

Alarge cheese pizza costs $18. each topping you add on costs $1.50. how much would it cost to get a large cheese pizza with cc toppings added? write your answer as an expression