\(A=18x\left(\frac{373737}{424242}+\frac{373737}{565656}+\frac{373737}{727272}\right)\)
\(=18x\left(\frac{37x10101}{42x10101}+\frac{37x10101}{56x10101}+\frac{37x10101}{72x10101}\right)\)
\(=18x\left(\frac{37}{42}+\frac{37}{56}+\frac{37}{72}\right)\)
\(=18x\frac{37}{18}\)
\(=37\)