When 3 is added 5 times to a number the result is 15 if the number is 0, otherwise this is not true. However, the amount added to the number is always 15. Let's say the variable x is our number and y is the result, then x+3+3+3+3+3=y. You can add all the 3's together now. So you have x+15=y. Now if the starting number is 0, you have 15=y, so the result is 15.
If: 6x+8 = 32 Then: x = 4
25
4
36
4x2 - x = 3
If: 6x+8 = 32 Then: x = 4
4 times a number added to 7 times the number equals 33
4
The number is 3
25
18 is a solution to the equation 4 plus 7 times a number where the result is 9 times that number.
The number is 20.
9
4
x = -.25
36
There is nothing in the description you have given which tells us the amount of that unspecified number, therefore, the answer could be anything. If you want to solve for an unknown number you need an equation. You might have said four times a number added to -9 subtracted from triple the sum of nine times the number and eight is equal to zero. Then we can solve the equation.