Răspuns :
11a+11b+54+x=1170
11a+11b+54+14=1170
11a+11b+68=1170
11a+11b=1170-68
11a+11b=1102
11(a+b)=1102
a+b=1102:11
a+b=100,(18)
7a+7b+7x=700
7a+7b+7*14=700
7a+7b+98=700
7a+7b=602
7(a+b)=602
a+b=86
x=14
a+b=?
b) 11×a + 11×b +56+x=1170
11(a+b)+56+14=1170
11(a+b)=1170-(56+14)
a+b=1100:11
a+b=100
c) 7×a+7×b+7×x=700
7(a+b+1)x14=700
7(a+b+1)x14=700:7
2(a+b+1)=100
a+b+1=100:2
a+b=50-1
a+b=49
Succes!