7.5a-5.16=3.1a+12
Since 3.1a contains the variable to solve for, move it to the left-hand side of the equation by subtracting 3.1a from both sides.
7.5a-5.16-3.1a=12
Since 7.5a and -3.1a are like terms, add -3.1a to 7.5a to get 4.4a.
4.4a-5.16=12
Since -5.16 does not contain the variable to solve for, move it to the right-hand side of the equation by adding 5.16 to both sides.
4.4a=5.16+12
Add 12 to 5.16 to get 17.16.
4.4a=17.16
Divide each term in the equation by 4.4.
(4.4a)/(4.4)=(17.16)/(4.4)
Cancel the common factor of 4.4.
a=(17.16)/(4.4)
Divide 17.16 by 4.4 to get 3.9.
a=3.9