Question

a) a×b =54 a×c =12 b- c=7 b) a×c =10 b×c=8 a-b =2 c) a×b=6 a×c =3 b×c=3

Answer 1

a) a*b=54..
    a*c=12   
    b-c=7     => b=c+7

a*(c+7)=54
a*c+7a=54
12*7a=54
7a=54-12
7a=42
a=42:7
a=6
6*c=12
c=12:6
c=2
b-2=7
b=2+7
b=9

6*9=54
6*2=12
9-2=7

b) a*c=10
    b*c=8
    a-b=2....=> a=b+2

(b+2)*c=10
b*c+2c=10
8*2c=10
2c=10-8
2c=2
c=2:2
c=1
b*1=8
b=8:1
b=8
a*1=10
a=10:1
a=10

10*1=10
8*1=8
10-8=2

c) a*b=6
    a*c=3....=> a=3:c
    b*c=2..=> b=2:c

(3:c)*(2:c)=6
(3*2):c=6
6:c=6
c=6:6
c=1
a*1=3
a=3:1
a=3
b*1=2
b=2:1
b=2

3*2=6
3*1=3
2*1=2

Answer 2

ba)a×b=54
a×c=12
scăzând relațiile
a×b-a×c=a(b-c)=42
b=54/a
c=12/a
54/a-12/a=7
42=7a
a=6
b=54:6
b=9
c=12/6
c=2
b)a×c=10
a=10/c
b×c=8
b=8/c
a-b=2
10/c-8/c=2
2=2c
c=1
b=8
a=10
c)a×b=6
a×c=3
b×c=3
b=6/a
c=3/a
6/a×3/a=3
18=3×a×a
a×a=6
a=√6

b=6/√6
b=√6
c=3√6/6
c=√6/2
verif:√6×√6=6
√6×√6/2=3
√6×√6/2=3