The ordered pair (-1, 4) is a solution to which of the pairs of equations? (1) (1) y = -x + 3, y = x + 1
(2) x - y = 2, x + y = - 6
(3) x + y = - 2, 7x - 4y = 8
(4) y = -x + 3, y = 2x + 6

The sum of two numbers is 86, and their difference is 20. find the two numbers

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.

Micheal is 4 times as old as brandon and is also 27 years older than brandon. how old is micheal