Since you don't state a problem I'll just use age problems for example.
Sheila is 4 times as old as Dave. In 5 years Sheila's age will be 9 years more than Dave's age. How old are Dave and Sheila?
Read the problem to determine what is being asked for as a final solution.
Define your unknown, like Let x = Dave's age. Do not say let x = Dave.
Sheila's age now = 4x
In 5 years
Dave's age will be x + 5
Sheila's age will be 4x + 5
If you add 9 years to Dave's age it will equal Sheila's age at that time SO
4x + 5 = x + 5 + 9 = x + 14
3x = 9
x = 3 Dave's age
4x = 12 Sheila's age
Eventually some part of the problem statement will say two values are now equal. Write those age statements on opposite sides of the equation.
Solve for x
Solve for any other ages called for.