Answer:
a = 16 and b = 13
Explanation:
The opposite sides of a parallelogram are congruent, so
CD = AB , that is
3a - 10 = 2a + 6 ( subtract 2a from both sides )
a - 10 = 6 ( add 10 to both sides )
a = 16
The diagonals of a parallelogram bisect each other, so
AO = CO , that is
2b = 26 ( divide both sides by 2 )
b = 13