Pls help- studying for midterms how would I solve:

1/5x+3/10=-4

(how to solve equations)

pls explain how you got an answer and identify answer
Thanks in advance:)

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?

Varies inversely with x. if y=8.5 when x=-1 find x when y=-1

David is standing on the sixth rung of a ladder while painting his house. which expressions represent a change in david’s position of 2 rungs on the ladder? choose exactly two answers that are correct. a. 6+2 b. 6-2 c. 2x6 d. 6/2