Someone help pls and thank you

Initially 100 milligrams of a radioactive substance was present. after 6 hours the mass had decreased by 4%. if the rate of decay is proportional to the amount of the substance present at time t, find the amount remaining after 24 hours. (round your answer to one decimal place.)

7x+8y=-18, 4x-9y=-3 solve the system of equations

Question 101 points)which equation in slope-intercept form represents the line that passes through (5, 1) and(-4,7)