Question 1044325
Let n be the total number of tosses.

Then the number of tails in the first 50 tosses is 0.70*50 = 35.

The number of tails in the remaining n - 50 tosses is 0.30*(n-50).

The total number of tails in the n tosses is 0.50n.

Hence,

35 + 0.30*(n-50) = 0.50n

===> 35 + 0.30n - 15 = 0.50n

===> 20 = 0.20n

===> n = 100, the number of tosses.