Sort:  

correct,
1+5 = 6 * 3 = 18
2+10=12 * 3 = 36
3 + 15= 18 * 3 = 54
therefore
4 + 20 = 24 * 3 = 72

Coin Marketplace

STEEM 0.24
TRX 0.12
JST 0.029
BTC 68016.16
ETH 3564.44
USDT 1.00
SBD 3.21