The sum of three numbers is 64. the second number is 3 more than the first. the third number is 11 less than twice the first. find the numbers.

The first number: x
The second number: x + 3
The third number 2 * x - 11
Sum of all numbers: 65

We can write it down as an equation:

65 = x + 3 + x + 2x - 11
65 = 4x + 3 - 11
65 = 4x - 8                         / + 8 (both sides)
73 = 4x                             / ÷ 6 (both sides_
x = 18,25

Doublecheck:

The first number: 18,25
The second number 18,25 + 3 = 21,25
The third number: 2 * 18,25 - 11 = 36,5 - 11 = 25,5
Sum of all numbers: 18,25 + 21,25 + 25,25 = 65, so it's correct :)