Answer:
3a-12c
Step-by-step explanation:
(5a-7c)-(2a+5c)
5a-7c-2a-5c
(5a-2a)+(-7c-5c)
3a-12c
Alternatively, you could have wrote down the formula instead of describing it with words. maybe then I could have helped you
Answer:
The 13th term is 81<em>x</em> + 59.
Step-by-step explanation:
We are given the arithmetic sequence:

And we want to find the 13th term.
Recall that for an arithmetic sequence, each subsequent term only differ by a common difference <em>d</em>. In other words:

Find the common difference by subtracting the first term from the second:

Distribute:

Combine like terms. Hence:

The common difference is (7<em>x</em> + 5).
To find the 13th term, we can write a direct formula. The direct formula for an arithmetic sequence has the form:

Where <em>a</em> is the initial term and <em>d</em> is the common difference.
The initial term is (-3<em>x</em> - 1) and the common difference is (7<em>x</em> + 5). Hence:

To find the 13th term, let <em>n</em> = 13. Hence:

Simplify:

The 13th term is 81<em>x</em> + 59.
Answer:
90
Step-by-step explanation:
bc i said so
X=7
7x-2=5x+12
+2. +2
7x=5x+14
-5x -5x
2x=14
÷2 ÷2
x=7