Question 1141329
<br>
small cylinder: radius r, height 7; total surface area {{{2(pi)r^2+2(pi)r(7)}}}<br>
large cylinder: radius r, height 3*7=21, total surface area {{{2(pi)r^2+2(pi)r(21)}}}<br>
The total surface area is 770:<br>
{{{4(pi)r^2+2(pi)r(28) = 770}}}<br>
With the "pi"s in that equation, the answer isn't going to be a "nice" number....  Use a calculator....