What is the slope for the equation y = -3x - 7

Giuseppi's pizza had orders for $931.00 of pizzas. the prices were $21 for a large pizza, 514 for a medium pizza, and $7 for a small pizza. the number of large pizzas was two less than four times the number of medium pizzas. thenumber of small pizzas was three more than three times the number of medium pizzas. how many of each size of pizza were ordered?

[15 points, algebra 2]simplify the complex fraction and find the restrictions.

The? half-life of a radioactive substance is 20 years. if you start with some amount of this? substance, what fraction will remain in 120 ? years