The answer is 117.5 or 117 1/2
Create a system if equations to solve this.
First equation:
25m + 24e = 220
Second equation:
m + e = 9
Then you must solve the second equation for a variable.
Change m + e = 9 to e = 9 - m.
Then substitute (9 - m) for e in the first equation.
So 25m +24e = 220 becomes 25m + 24(9 - m) = 220.
Now you can solve the first equation because the only variable in it is m.
25m + 24(9 - m) = 220 (Original equation)
25m + 216 - 24m = 220 (Distribute)
m + 216 = 220 (Combine like terms)
m = 4 (Simplify)
Now plug in 4 for m in the second equation.
m + e = 9 (Original equation)
(4) + e = 9 (Substitute)
e = 5 (Simplify)
m represents Math Books and e represents English Books, so Nicole purchased 4 Math Books and 5 English Books.
Answer:
<h3> 26²/₃ liters of 15% acid and 13¹/₃ liters of 33% acid</h3>
Step-by-step explanation:
Concentration Amount of Amount
of Solution Solution (L) of Acid
15% x 0.15x
33% y 0.33y
21% 40 0.21•40
x + y = 40 ⇒ x = 40 - y
0.15x + 0.33y = 0.21•40
0.15(40 - y) + 0.33y = 0.21•40
6 - 0.15y + 0.33y = 8.4
0.18y = 2.4
y = 13¹/₃
x = 40 - 13¹/₃ = 26²/₃
Answer:
7020
Step-by-step explanation:
The letter could be any 1 of the 26 and it could be placed in any 1 of 3 places so this makes 26*3 = 78 possibilities.
For each of these there is any one of permutations of 2 digits from 10
= 10P2 = 10! / 8! = 10*9 = 90.
So the answer is 78 * 90 = 7020.
Note I am assuming that the 2 digits picked are different - no duplicates.
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