Answer: He bought 1 magazine and 3 comic books.
Step-by-step explanation: If comic books cost $1 and magazines cost $3, the equation for the problem should look like this: 2(m) + 1(c) = 5, since you know that the brother spent $5 in total. "m" represents the number of magazines purchased while "c" represents the number of comic books purchased. If you plug in 1 for "m" and 3 for "c", the equation would be true and would equal a total of $5. Also, 1 magazine and 3 comic books would mean that the little brother did, in fact, purchase 4 items.
A) I would make the positive integer x and then form an equation.
x + 30 = x^2 - 12
x + 42 = x^2
0 = x^2 - x - 42 this can be factorised
(x - 7) ( x + 6) Therefore x = 7 or x = -6
Since the question asks for a positive integer the answer is 7.
B) two positive numbers x and y.
X - y = 3
x^2 + y^2 = 117
Use these simultaneous equations to figure out each number.
Rearrange the first equation
x = y + 3
Then substitute it into the second equation.
(y+3)^2 + y^2 = 117
y^2 + 6y + 9 + y^2 = 117
2y^2 + 6y - 108 = 0
then factorise this.
(2y - 12) (y + 9)
This means that y = 6 or y = -9 but it’s 6 because that’s the only positive number.
Use y to find x
x = y + 3
x = 6 + 3
x = 9
So the answers are x = 9 and y = 6.
There are 20 C3 possible ways to choose 3 books to read.
There are 5 C3 possible ways to choose 3 mysteries to read.
The probability that Mariah will not choose all mysteries can be expressed as 1-5C3/20C3. (These 3 Choices Are True)
There are 1 C3 possible ways to choose 3 books that are not all mysteries.
The probability that Mariah will choose 3 mysteries can be expressed as 1/5C3.
(These 2 Choices Are False)
Hope This Helps
Subtract 1:
x/4=2
multiply by 4:
x=8 which is the answer
