76. Xi Xi bought 3 table tennis balls and 2 badminton shuttlecocks for 15.5 yuan, Wang Wang bought 2 table tennis balls and 3 badminton shuttlecocks for 17 yuan. If buying 4 table tennis balls and 4 badminton shuttlecocks, it would cost $\qquad$ yuan.
Reference answer: 26
Key point: Equivalent substitution