book Maths Puzzle Numerical Ability

Can someone tell me if I did this correctly

3(x-5) + 3x = 4x + 5

I get an answer of x = 10

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This new math sure gets me. I am a senior and trying to answer this question.
[2x(9+7)-4]/7=
Thank you. can someone please tell me if these are correct, thank you
T=v^2p^2/c if v=3, p=2 and c=4
MY ANSWER T=50
T=xh^2 if x=2 and h=5
MY ANSWER T=18