Answer:
15
Step-by-step explanation:
a represents 15
13/a= 39/45
We multiply 13*3 to get the denominator 39 on the right hand side.
So this means if we multiply the numerator by 3, we also multiply the denominator by 3 as well.
So, if 13*3= 39, then what number will give us 45?
To get that number, we divide 3 into 45 to get 15
Therefore a is 15
