What is the measure of ∠a ?
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°
image shows a circle with inscribed quadrilateral a b c d. the measure of angle c is 74 degrees.

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.

Azul has 4 green picks and no orange picks.you add orange picks so that there are 2 orange picks for every 1 green pick.how many picks are there now.

What is the surface area of the sphere?