Explicație pas cu pas:
2) A
3) a+b=12 ->a=12-b
3×a+5×b=50
3×(12-b)+5×b=50
36-3×b+5×b=50
36-2×b=50
2×b=50-36
2×b=14
b=14:2=7 B
4) 7¹⁴×5²:7¹²=7²×5²=49×25=1225 C
1) l zi cheltuie a/2+10
a-(a/2+10)=a-(a+20)/2=2×a-a+20/2=a+20/2 (restul)
ll zi cheltuie a+20/2:3+16=a+20/2×1/3+16
a+20/6+16=a+20/6+96/6=a+116/6
a/2+10+a+116/6+24=a
3×a+60+a+116+114=6×a
4×a+190=6×a
2×a=190
a=190:2
a=95 lei
