"In a recent survey it was found that 50% of investors placed their money in Apple shares while 60% invested in Google. Of the people surveyed, 15% invested in neither of these.

Find the proportion of investors that had both Apple and Google shares."

I have tried calculating as two independent events:

$$Pr(A\cap B)=Pr(A)\cdot Pr(B)=0.5\cdot 0.6=0.3,$$

which is incorrect.

According to the answers, the correct answer should be 0.25, but I'm not able to find this at all. Any help is greatly appreciated!

Find the proportion of investors that had both Apple and Google shares."

I have tried calculating as two independent events:

$$Pr(A\cap B)=Pr(A)\cdot Pr(B)=0.5\cdot 0.6=0.3,$$

which is incorrect.

According to the answers, the correct answer should be 0.25, but I'm not able to find this at all. Any help is greatly appreciated!