In the first part of your equation you have:
From their opening dates, musical A and musical B have together made $7.5 billion worldwide.
Which will give you the equation: A+ B= $7.5
The second part states:
Musical A has made $0.6 billion more than twice what musical B has made.
Which the equation here would be: A = 2B + $0 .6
Best way to do this is using substitution which uses:
2B +0 .6 + B = 7.5
Solve for B which gives
3B+0.6= 7.5
3B= 6.9
B= 2.3
Now you can plug B in for any of the two equations easiest one is A+B= $7.5
It now leads you with:
A+2.3= 7.5
Solve for A:
A= 5.2
Hope that helps!