Algebraic set up.
6X + 18 = 168
subtract 18 from each side
6X = 150
X = 25
check
6(25) + 18 = 168
150 + 18 = 168
168 = 168
checks
25
4 times a number added to 7 times the number equals 33
4
The number is 3
The number is 20.
9
4
169
x = -.25
36
6
Then the number is 20.5