Write the following statements in the form of equations and solve the equations.
1.The sum of three times x and 10 is 40.
2.One third of a number plus 7 is 10.
3.The sum of three numbers is 20 .First number is 8, third number is 3 times of the second number.
4.If you subtract 8 from 7 times of a number, you get 6.