Answer :

Answer:

Make a Venn diagram for this

it would look something like this

So this means you have to find the intersection of both the subjects

and you know that if you do 50 - econ union government = 7

as those students take neither

so just minus 17 - 7 = 10

30 -7 = 23

and add 23 +10 = 33, 50 - 33 = 17 so 17 take both the subjects

See the diagram it will be clear i hope

View image Smarty90