The half-life of a radium isotope is 1,600 years. after 4,800 years, approximately how much of an original 10.0kg sample of this isotope will remain

Nell has a sales clerk job that pays $12 per hour for regular gas work hours. she gets double time for any hours over 40 that she works in a week. how many hours did nell work if her weekly pay was $744

In trapezoid efgh, m∠hef=(4x2+16)∘ and m∠gfe=(5x2+12)∘. find the value of x so that efgh is isosceles. i'm desperate.

What is the area of the triangle 10 13 12