book Maths Puzzle Numerical Ability

How do figure this problem out? 3(3x+1)-(x-1)=6(x+10)
and this problem 0=5(7-x)+12x

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book Other Question

5x+7 = 6(x-2)-4(2x-3) solve for all unknown variables:
RmTm=RrTr ... these are what they give you... Rm=8, Rr=2, Tr=5-Tm