Oi :)
\(\frac{t+y}{2}=15 \\ \\ t+y=15*2 \\ t+y=30\)
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\(\frac{w+x}{2}=15 \\ \\ w+x=15*2 \\ w+x=30\)
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Logo:
\(\frac{t+y+w+x}{4}=??? \\ \\ \frac{30+30}{4} \\ \\ \frac{60}{4} \\ \\ 15\)
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Answer = 15
Boa Noite. Bons Estudos !