Verified answer

Ответ:

d=7

Пошаговое объяснение:

a1+a1+4d=24

(a1+d)(a1+2d)=60

2a1+4d=24

(a1+d)(a1+2d)=60

a1+2d=12

a1= 12-2d

(12-2d+d)(12-2d+2d)=60

(12-d)*12=60

12-d=5

d=7