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We are given –
- And also value of y's given. So, just put the value of y in the given equation.
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- Henceforth, value of x is 7.
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An arithmetic sequence starts with one number and you add the common difference to the previous term to get the current term
So...
f(x)=mx+b
m=common difference
b=starting point
f(11)=125=11m+b
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f(1)=5=1m+b
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120=10m
Divide both sides by 10
12=m
Your common difference is 12.
Are you asking the equation or the answer
9 is subtracted from the sum of 5 and a number