What is 2n + -3 + 7 + 9

Two streets intersect at a 30- degree angle. at the intersection, the are four crosswalks formed that are the same length. what type of quadrilateral is formed by the crosswalks?

Ascientist has 50 grams of a radioactive element. the amount of radioactive element remaining after t days can be determined using the equation (1) after two days the scientist receives a second shipment of 50 grams of the same element. the equation used to represent the amount of shipment 2 remaining after t days is 10) - 50 which of the following is an equivalent form of the expression for the amount remaining in shipment 2? what’s the answer?

Plz 20 points polynomials 1: subtract and simplify (–y^2 – 4y – 8) – (–4y^2 – 6y + 3) 2: multiply and simplify 2x^2 y^3 z^2 · 4xy^4 x^2 3: multiply and simplify (x – 4) (x2 – 5x – 6)