For problem #2, you correctly set up the equation 128 = x(800). To find the value of x, you need to divide both sides of the equation by 800. By simplifying, you get:
x = 128/800
x = 0.16
Since the question asks for the percentage, you need to multiply the result by 100:
x = 0.16 * 100
x = 16%
So, you are correct. The solution is that 128g is 16% of the 800g solution.
For problem #3, the equation should be set up as:
Principal (5000) = Rate (r) * Time (4 years)
The interest earned (400) is not included in this equation because it is the result of the interest rate over the given period of time. By rearranging the equation, you can solve for the interest rate (r):
r = Principal / Time
r = 5000 / 4
r = 1250
So, the interest rate per year is 1250.
For problem #4, you set up the equation correctly as:
72 = 0.12x
To solve for x (the paycheck amount), divide both sides of the equation by 0.12:
x = 72 / 0.12
x = 600
So, the paycheck amount is $600.
I hope this clarifies the solutions for you! Let me know if you have any further questions.