Explicație pas cu pas:
49x28=1372
31x14=434
1372-434=938 (B)
567x3=1701
45x11=495
1701+495=2196 (C)
11x12=132
91x13=1183
132+1183=1315
2107-1315=792 (D)
113x19=2147
74x86=6364
6364+2147=8511
8511-3021=5490 (E)
67x34=2278
24x25=600
2278-600=1678
23x11=253
1678+253=1931 ( F)