Answer:
27
Step-by-step explanation:
Let <em>g </em>be Gabrielle's age and <em>m </em>be Mikhail's age.
We can turn the statements the problem gives us into mathematical expressions to help us solve.
Gabrielle's age is two times Mikhail's age:
<em>g </em>= 2<em>m</em>
The sum of their ages is 81:
<em>g </em>+ <em>m </em>= 81
This gives us a system of equations that will allow us to solve for Gabrielle's age.
<em>g </em>+ <em>m </em>= 81
(2<em>m</em>)<em> </em>+ <em>m </em>= 81
3<em>m </em>= 81
<em>m</em> = 
<em>m </em>= 27
If we need to solve for Gabrielle's age, we can do the following.
<em>g </em>= 2<em>m</em>
2(27)<em> </em>= <em>g</em>
54 = <em>g</em>
g = 54
Mikhail's age is 27.
Gabrielle's age is 54.
Answer:
1199
Step-by-step explanation:
There are 22 terms in the sum:
23 + 26 + 29 + ... + 80 + 83 + 86 =
= (23 + 86) + (26 + 83) + ... + (53 + 56)
= 109 + 109 + ... + 109
= 11(109)
= 1199
Answer:
Anything
Step-by-step explanation:
5n - 10 = 5n - 10
It doesn't matter what you put in for n, the equality can never be anything but an equality.
Suppose n = 10,000,000
Then 5*10,000,000 - 10 = 5*10,000,000
Simple. Just add/subtract each term. 4n-2n=2n. 8m+7m=15m.
This is very basic stuff.