The probability is 4 out of 14
35a + 25c = 2660
a = 2c
35(2c) + 25c = 2660
70c + 25c = 2660
95c = 2660
c = 2660/95
c = 28 <=== there were 28 children tickets
a = 2c
a = 2(28)
a = 56 <== there were 56 adult tickets
9 has factors of 3*3.
2 is prime, so no factors.
from those two denominators, we can get the LCD of hmmm simply their product, namely 18.

now, recall that, to get the mixed fraction, we divide 89 ÷ 18, the quotient goes up front, the "4", and the remainder is the one atop, the "17".
If 2 Lines are crossing together to make 2 pairs of Vertical Angles, the sum of all 4 Angles will always be equal to 360°.