First take his 10 small boxes and multiply them by 12 (the amount of packets in a small box) and divide it by 50 (the amount of packets in a large box)
10x12=120
120/50=2 r.20
So you have 2 large boxes with 20 left over, but you can put those into small boxes. So you got 2 large boxes, 1 small box and 8 leftover.
Or the short answer, he can fill 2 large boxes.
Brainliest my answer if it helps you out
