Answer
$49$
Work Step by Step
Let $x$ be the number of members and $y$ be the original share, then $x\cdot y=1470=(x-7)(y+5)=xy-7y+5x-35$ So $y=\frac{1470}{x}$, thus $xy-7y+5x-35=1470-\frac{10290}{x}+5x-35=1470\\-10290+5x^2-35x=0\\x^2-7x-2058=0\\(x-49)(x+42)=0$ Thus $x=49$ or $x=-42,$ but the negative value doesn't make sense, thus there are $49$ members.
(Check: $49\cdot30=(49-7)\cdot(30+5)=42\cdot35=1470$)
