Answer:
90
Explanation:
a times by b is equal to 3600 and b divided by a is equal to 4/9 which means that a must be a mulitiple of 4 and b must be a multiple of 9. An easy multiple of 4 and a easy mulitple of 9 that times together eqaul 3600 is 90 and 40. So therefore a= 90