BT: Tính
a) 3x - 9y²
b) 4(2x-y)-x(y-2x)

Seymour is twice as old as cassandra. if 16 is added to cassandra’s age and 16 is subtracted from seymour’s age, their ages become equal. what are their present ages? show !

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.

Given: jk ||lm prove: _2 = 27 statement justification 1. jk ||lm 1. given 2.26 = 27 3.22 = 26 2. 3. 4. _2 = 27 4. corresponding angles theorem transitive property of equality vertical angles theorem substitution property of equality