first question
7(2x-3)+3=24
second question
5+3x=7(x+3)
third question
3(8-6n)=41
$\displaystyle 7(2x - 3) + 3 = 24$
$\displaystyle 7(2x - 3) + 3 - 3 = 24 - 3$
$\displaystyle 7(2x - 3) = 21$
$\displaystyle \frac{1}{7} \cdot 7(2x - 3) = \frac{1}{7} \cdot 21$
$\displaystyle 2x - 3 = 3$
$\displaystyle 2x - 3 + 3 = 3 + 3$
$\displaystyle 2x = 6$
$\displaystyle \frac{1}{2} \cdot 2x = \frac{1}{2} \cdot 6$
$\displaystyle x = 3$
Try the other ones. They are very similar in principle.
-Dan