Answer :
[tex]x- \ angelfish\\
y-\ goldfish\\
z-\ guppies\\\\
\left\{\begin{array}{l} x+y=149\\2x=z\\2(y-35)=x \end{array} \\\\
2y-70+y=149\\
3y-70=149\ \ |Add\ 70\\
3y=219\ \ |:3\\y=73\\\\
x=149-73\\
x=76\\
z=2x\\
z=2*76=152\\\\
All\ fishes:\\
x+y+z=76+152+73=301\\
After\ selling\ 35\ goldfishes\ there\ are\ 266\ fishes\ in\ aquarium.
[/tex]
149goldfish and 149angilfish
Guppies Twice as many angilfish
So 149angilfish
× 2
-------------
298guppies
298
+148
--------
447total fish 447
- 35
---------
414 left over