Answer:
Step-by-step explanation:
If the trapezoid is isosceles, angles A and C are supplementary, so ...
... (4x+4) +(7x+11) = 180
... 11x +15 = 180 . . . . . . collect terms
... 11x = 165 . . . . . . . . . subtract 15
... x = 15 . . . . . . . . . . . . divide by the coefficient of x
And angles C and E are congruent.
... 4·15 +4 = 21y +1
... 63 = 21y . . . . . subtract 1
... 3 = y . . . . . . . . divide by the coefficient of y
