Question

the sum of 3 times of a number and 3 is 7 find the number

Answer 1

let the "number" equal "n" just to make things easier:
3 times a number -- 3 * nSum -- add
Sum of 3 times a number and 7 -- 3n + 72 times the number -- 2 * n
Now, let's put it all together:
3n + 7 = 2n
Combine like terms by subtracting '3n' on both sides:
7 = -n
Divide by -1 to get 'n' by itself:
n = -7

Answer 2

let the number be x.
3x+3=7
=>3x=7-3
=>3x=4
=>x=4/3
=>x=1.333333333