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?
A) 2(-3x - 4) + 3x =- 21
B) 2(3x - 4) + 3x =- 21
C) 2x - 3(-3x – 4) =- 21
D) 2x - 3(3x - 4) =- 21

Is this a polynomial function? i need to know asap

In one day there are too high tides into low tides and equally spaced intervals the high tide is observed to be 6 feet above the average sea level after six hours passed a low tide occurs at 6 feet below the average sea level in this task you will model this occurrence using a trigonometric function by using x as a measurement of time assume the first high tide occurs at x=0. a. what are the independent and dependent variables? b. determine these key features of the function that models the tide: 1.amplitude 2.period 3.frequency 4.midline 5.vertical shift 6.phase shift c. create a trigonometric function that models the ocean tide for a period of 12 hours. d. what is the height of the tide after 93 hours?

Answer asap evaluate 4-0.25g+0.5h4−0.25g+0.5h when g=10g=10 and h=5h=5.