Mu$$strame c$$mo resolver

It is observed that the severity of a Professional Liability insurance X$,$ behaves as a mixture of two exponential v$.$a$.$ with expected values $$of $200$ and $200+$ a$,$ with a $>0.$ Information is available on the mean and total variance:

E$[$X$]=210$

var$($X$)=45,200$

If a standard deductible of $60$ were to be applied, what percentage of the total losses would not apply for coverage?

$($A$)30\%$

$($B$)70\%$

$($C$)25\%$

$($D$)75\%$

$($E$)$ N$.$A$.$