Solve all four questions and PLEASE show work... I will mark you brainliest and rate you five stars

Chip worked at the animal shelter for 6 hours each week for several weeks. he worked for a total of 42 hours. which of the following can be used to find the number of weeks chip worked at the animal shelter?

Will used 20 colored tiles to make a design in art class. 5/20 of his tiles were red. what is an equivalent fraction for the red tiles?

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.