ANSWER
18
EXPLANATION
Let the number be x.
Fives times the sum of the number and three means:
5 * (x + 3)
=> 5(x + 3)
Three times the difference of twice the number and one means:
3 * [(2 * x) - 1]
=> 3(2x - 1)
Those two expressions are equal.
That is:
5(x + 3) = 3(2x - 1)
Expand the bracket:
=> 5x + 15 = 6x - 3
Collect like terms:
6x - 5x = 15 + 3
x = 18
The number is 18.
