To find the first customer who will receive both a chocolate lolly and a box of truffles, we need to find the least common multiple (LCM) of 70 and 336. The LCM is the smallest number that is divisible by both 70 and 336.
The LCM of 70 and 336 is 1680.
Therefore, the 1680th customer will be the first to receive both a chocolate lolly and a box of truffles.