Let the cost of 1 burger, 1 shake and 1 fries be a, b and c.
Then
3a + 7b + c = 120 ... (i)
4a + 10b + c = 164.5 ... (ii)
After subtracting (i) from (ii)
a + 3b = 44.5 ... (iii)
Multiplying (iii) by 4 and subtracting (ii) from it, we find
2b – c = 13.5 ...(iv)
Subtracting (iv) from (iii),
we get a + b + c(cost of one burger, one shake, and one order of fries)= 31.
Hence,Option (1)31 is the Answer.