Solve for x
x=64
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\frac{1}{720}+\frac{1}{7!}=\frac{x}{8!}
The factorial of 6 is 720.
\frac{1}{720}+\frac{1}{5040}=\frac{x}{8!}
The factorial of 7 is 5040.
\frac{7}{5040}+\frac{1}{5040}=\frac{x}{8!}
Least common multiple of 720 and 5040 is 5040. Convert \frac{1}{720} and \frac{1}{5040} to fractions with denominator 5040.
\frac{7+1}{5040}=\frac{x}{8!}
Since \frac{7}{5040} and \frac{1}{5040} have the same denominator, add them by adding their numerators.
\frac{8}{5040}=\frac{x}{8!}
Add 7 and 1 to get 8.
\frac{1}{630}=\frac{x}{8!}
Reduce the fraction \frac{8}{5040} to lowest terms by extracting and canceling out 8.
\frac{1}{630}=\frac{x}{40320}
The factorial of 8 is 40320.
\frac{x}{40320}=\frac{1}{630}
Swap sides so that all variable terms are on the left hand side.
x=\frac{1}{630}\times 40320
Multiply both sides by 40320.
x=\frac{40320}{630}
Multiply \frac{1}{630} and 40320 to get \frac{40320}{630}.
x=64
Divide 40320 by 630 to get 64.
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