He earned $199,423 in interest.
His total would be $207,423.
6x+3=18
subtract 3 from both sides
6x=15
divide both sides by 6
x=2.5
5(4x-5)=155
distribute the 5
20x-25=155
add 25 to both sides
20x=180
divide both sides by 20
x=9
Because in the numerator and denominator of the fraction 1a/3a, you're able to simplify that and get 1/3. There is actually no solution to the problem you're asking. You're unable to find out what (a) equals.