87 for t-shirts and 243 for sweatshirts, the total cost is 330
Answer:
Tina can select and answer the essay questions on her test in 35 ways.
Step-by-step explanation:
The order in which she chooses the questions is not important. For example, choosing questions 1, 3 and 7 is the same as choosing 7, 3 and 1. So we use the combinations formula to solve this question.
Combinations formula:
is the number of different combinations of x objects from a set of n elements, given by the following formula.
In this question:
Three questions from a set of 7. So
Tina can select and answer the essay questions on her test in 35 ways.
Let's have the first number, the larger number, be <em>x</em>. We'll have the second, smaller number be <em>y</em>.
We know that x = y + 6, since x is 6 greater than y.
We also know that 330 = x + y.
Because x = y + 6, 330 = y + 6 + y, which simplifies to 330 = 2y + 6.
Now all we need to do is simplify the equation. First, we subtract 6 from both sides:
330 - 6 = 324
2y + 6 - 6 = 2y.
So we have 324 = 2y. Then we divide both sides by 2 to get:
162 = y
Plug in y = 162 into the equation x = y + 6 to get:
x = 162 + 6
x = 168
Let's check to make sure our answer is right. 168 is 6 more than 162. 162 + 168 equals 330. So our two numbers are 168 and 162.
-3x + 9 - 4 = x + 3 + 2x
-3x + 9 - 4 = 3x + 3
9 - 4 = 6x + 3
5 = 6x + 3
2 = 6x
1/3 = x
