There is nothing attached
Since Sarah’s age is 2x of Bob’s age (which is 42) Sarah is 84.
8.5b.
7a= 5a +3b
-5a -5a
2a = 3b
/2
a= 1.5b
Solve by substitution and you get;
8.5b=8.5b
Because of the lack of constants in the equation there isn't a definite answer.