Question 1117067

given:
{{{ABCD}}} is an {{{isosceles}}} trapezoid with diagonals that intersect at point {{{P}}}. 

If 
{{{AC = 7y - 30}}}
{{{BD = 4y + 60}}}
 and 
{{{CD = 5y + 14}}}

 solve for {{{y}}}  

recall: an {{{isosceles}}} trapezoid when both angles coming from a parallel side are equal,  the sides that aren't parallel are equal in length, and the diagonals of an isosceles trapezoid are congruent

in your case, the diagonals are {{{AC}}} and {{{BD}}}, so you have

{{{AC =BD}}}
{{{7y - 30=4y + 60}}} ....solve for {{{y}}}

{{{7y -4y =30+ 60}}}

{{{3y =90}}}

{{{y =90/3}}}

{{{y=30}}}

answer:
B.{{{30}}}