3600 if you multiply 40 to 80<span />
Answer:
y = -6x + 30
Step-by-step explanation:
The inicial value you have is $30, so this will be the value of y after 0 weeks, that is, x = 0
After one week, you spend $6, so you will have y = 30 - 6 = 24 when x = 1.
With these pair of values, we can find the linear equation:
y = ax + b
for x = 0, y = 30:
30 = a*0 + b
b = 30
for x = 1, y = 24:
24 = a*1 + 30
a = 24 - 30 = -6
So, our equation is:
y = -6x + 30
Answer:
y=5x-7
-3x-2y=-12
Step-by-step explanation:
-3x-2(5x-7)=-12
-3x-10x+14=-12
-13x+14=-12
-13x=-26
y=5x-7+5x2-7=10-7=3
It will take approx.65 of caffeine remaining after 6 hours
Answer:
95
Step-by-step explanation:
Let x represent the ones digit. The tens digit will be higher, because reversing the digits results in a lower number. Its value is (14 -x). The given relation is ...
(10(14-x) +x) -(10x +(14 -x)) = 36 . . . . reversing the digits gives 36 less
140 -9x -9x -14 = 36 . . . . eliminate parentheses
90 = 18x . . . . . . . . add 18x-36
5 = x . . . . . . ones digit
14-5 = 9 . . . tens digit
The original number is 95.
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<em>Check</em>
95 -59 = 36
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<em>Additional comment</em>
The difference in value when the digits of a 2-digit number are reversed is always 9 times the difference in the digits. This means the difference in the digits is 36/9 = 4. Since the sum of digits is 14, the two digits are (14+4)/2 = 9 and (14-4)/2 = 5. 95 is the number of interest.
The solutions to a "sum and difference" problem are half the sum and half the difference of the given sum and difference. That is how we know the larger digit is (1/2)(14 + 4), for example.
We worked this "the hard way" using the above equation. It can actually be worked in your head if you're familiar with these generic solutions.
