First of all it is always a good idea to graph a question like this one. Here are the three graphs
y = x^4 - x^2 Color: Red This is the base graph
y = x^4 - x^2 - 4 Color Blue This has - 4 added to it.
y = x^4 - x^2 + 4 Color Green This has 4 added to the base graph
Which one is correct? The red and blue one are not. The graph you want is plotted upward from the base graph. The base graph (red nothing added to it) is not right because it has points on the x axis. The graph you want does not.
The same is true of the blue graph. It cuts the x axis. That only leaves the green one.
Answer: C
Think about it. What plus 35 is 57? Or what is 57 minus 35? The answer is 22.
1. The answer to addition problems is referred to as the sum, multiplication as the product, subtraction as the difference and division as the quotient. So...False.
2. You could turn the percent into a decimal, after rounding to 25, and multiply it by 121 to get about 30. However, I find it easier to just move the decimal one place to the left and multiply the product by how many tens are in the estimated percent.
10% = .10 .10 x 121 = 12.1 x 3 = 36.3 Which is still rather close and doesn't need a calculator.
3. Using the methods earlier, I'd say the best estimate is 45.