"The Diagram:"
color(blue)("We know that the volume of the whole solid is" 70pi
(or)
color(red)("The sum of the volumes of the cone and cylinder is " 70pi
"Now lets set up an equation for solving the question"
color(brown)("Volume of cone"=1/3 pir^2h=v_1
color(brown)("Volume of cylinder"=pir^2h=v_2
"(Where "h" is the height and "r" is the radius)"
"Known values of the variables":
color(violet)(h color(violet)("of" color(violet)(v_1=60
color(violet)(h color(violet)("of" color(violet)(v_2=15
"We need to find the value of" pir^2 "which is the base"
:.color(orange)(v_1+v_2=70pi
rarr1/3pir^2h+pir^2h=70pi
rarr1/3pir^(2)60+pir^(2)15=70pi
rarr1/cancel3^1pir^(2)cancel60^20+pir^(2)15=70pi
rarrpir^(2)20+pir^(2)15=70pi
"Rewrite the equation"
rarr20pir^(2)+15pir^(2)=70pi
rarr35pir^2=70pi
rarrpir^2=(cancel70^2pi)/cancel35^1
rArrcolor(green)(pir^2=2pi