I think the answer is 80.

BCD counter counts from 0-9 and starts again (mod 10).

Binary counter counts from 0-15 and starts again (mod 16)

Lets assume initially Binary counter at value 0000.

BCD counter can count on clock pulses, Binary counter increments only when Q3 becomes 1 (ie 8 and 9)

See the figure , I am including, we have 8 cycles of 10 different values . Therefore answer is 80.