If 21 is added to a number the result is 40 less than twice the number what is the number?

If 21 is added to ( + 21) a number (x) the result (=) is 40 less than ( - 40) twice the number (2x)

x + 21 = 2x - 40 Add 40 to both sides

x + 61 = 2x Subtract x from both sides

61 = x Switch the sides to make it easier to read

x = 61