Question

nine added to thrice a number a whole number gives 45. find the number

Answer 1

3x+9=45
3x=45-9
3x=36
x=12

Answer 2

let the no. be = x
now,
9+3x=45
3x =45-9
3x =36
x =36/3
x =12
so, the no. would be 3×12=36