each variable represents one number.

find the value of each variable.
a+5=11
a-b=2

3xc=12
c divide d=4

a + 5 = 11

a - b = 2.

a = 11 - 5 = 6.
6 - b = 2,
b = 6 - 2 = 4.

3c = 12
c/d = 4.

3c = 12,
C = 4.
4/d = 4,
4d = 4,
d = 1.