9:Using the substitution method, Vito is solving the following system of
equations algebraically:
y + 3x = -4
2x - 3y = -21
-Which equivalent equation could Vito use?
(1) 2(-3x – 4) + 3x = -21
(3) 2x - 3(-3x – 4) = -21
(2) 2(3x – 4) + 3x = -21
(4) 2x - 3(3x - 4) = -21

Refer to interactive solution 17.45 to review a method by which this problem can be solved. the fundamental frequencies of two air columns are the same. column a is open at both ends, while column b is open at only one end. the length of column a is 0.504 m. what is the length of column b?

The larger of two number is 4 less than twice the smaller number. the sum is 41. find the numbers

Abacteria population is tripling every hour. by what factor does the population change in 1/2 hour? select all that apply