Answer:
1. x + 5 = 12
2. 2x = 54
Explanation:
Let
The unknown number = x
1. The sum of a number and 5 is 12.
x + 5 = 12
x = 12 - 5
x = 7
2. Twice a number is 54
2x = 54
x = 54/2
x = 27
3. Thrice a number increase by 2 is less than 50.
3x + 2 < 50
3x < 50 - 2
3x < 48
x < 48/3
x < 16
4. One half the sum of a number and 4 is less than 28.
1/2(x + 4) < 28
5. A number increased by one-third of the number is 5.
x + 1/3x = 5