MySQL 8.0

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create table price(idRequest int,  idPair int, idExchangePlatform int,  lastPrice int);
insert into price values(    1,         1,               1,               95);
insert into price values(    1,         1,               2,               100);
    insert into price values(1,         1,               3,               40);
    insert into price values(2,         1,               1,               80);
    insert into price values(2,         1,               2,               250);
    insert into price values(2,         1,               3,               10);
    insert into price values(3,         1,               1,               110);
    insert into price values(3,         1,               2,               300);
    insert into price values(3,         1,               3,               60);
    insert into price values(1,         2,               2,               800);
    insert into price values(1,         2,               3,               1300);
    insert into price values(2,         2,               2,               1110);
    insert into price values(2,         2,               3,               1950);

idRequest	idPair	idEP_a	idEP_b	lastPrice_sum
1	1	1	2	195
1	1	2	3	140
1	1	1	3	135
2	2	2	3	3060