So if the equation you showed is a given, then you are on the right track. I'm trying to figure out where financial investment spending is in the equation, though?
I found this: The following equation is used to calculate the GDP: GDP = C + I + G + (X – M) or GDP = private consumption + gross investment + government investment + government spending + (exports – imports). ... It transforms the money-value measure, nominal GDP, into an index for quantity of total output.
72,000,000+12,000,000+25,000,000+ G + 5,000,000 = 123,000,000
It's easier to solve it without the zeros:
G=123 - 72- 12 - 25 - 5
G= 9 or 9,000,000 is government spending
Remember that (X-M) is NET EXPORTS. They will either give you exports and imports so that you have to subtract, or net exports that you can just plug in. Make sense?